polish(android): grouped Settings cards + ConnectScreen error banner & search indicator

- Settings: flat list -> Display / Host / Audio / Overlay sections in outlined
  cards (SettingsGroup + ToggleRow helpers) with section headers.
- ConnectScreen: connection errors now show in a filled errorContainer banner
  (was plain red text lost in the layout), and a "Searching the local network..."
  spinner appears while discovery is active but nothing's turned up yet.

Verified locally: ./gradlew :app:assembleDebug BUILD SUCCESSFUL.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/android/app/src/main/kotlin/io/unom/punktfunk/ConnectScreen.kt

@@ -22,6 +22,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.GridItemSpan
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
@@ -40,6 +41,7 @@ import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.ModalBottomSheet
 import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.rememberModalBottomSheetState
@@ -228,12 +230,21 @@ fun ConnectScreen(settings: Settings, onConnected: (Long) -> Unit) {
                                 )
                             }
                         } else {
-                            Text(
-                                it,
-                                style = MaterialTheme.typography.bodySmall,
-                                color = MaterialTheme.colorScheme.error,
-                                textAlign = TextAlign.Center,
-                            )
+                            // Result/error: a filled error container reads as a real failure banner,
+                            // not just red text lost in the layout.
+                            Surface(
+                                color = MaterialTheme.colorScheme.errorContainer,
+                                shape = MaterialTheme.shapes.medium,
+                                modifier = Modifier.fillMaxWidth(),
+                            ) {
+                                Text(
+                                    it,
+                                    style = MaterialTheme.typography.bodyMedium,
+                                    color = MaterialTheme.colorScheme.onErrorContainer,
+                                    textAlign = TextAlign.Center,
+                                    modifier = Modifier.padding(horizontal = 16.dp, vertical = 12.dp),
+                                )
+                            }
                         }
                         Spacer(Modifier.height(16.dp))
                     }
@@ -282,6 +293,26 @@ fun ConnectScreen(settings: Settings, onConnected: (Long) -> Unit) {
                 }
             }
 
+            // Active-discovery hint: when we're scanning but nothing's turned up yet, show it's
+            // working rather than looking idle/empty.
+            if (nearbyGranted && discovered.isEmpty()) {
+                item(span = { GridItemSpan(maxLineSpan) }) {
+                    Row(
+                        modifier = Modifier.fillMaxWidth().padding(vertical = 12.dp),
+                        horizontalArrangement = Arrangement.Center,
+                        verticalAlignment = Alignment.CenterVertically,
+                    ) {
+                        CircularProgressIndicator(modifier = Modifier.size(16.dp), strokeWidth = 2.dp)
+                        Spacer(Modifier.width(8.dp))
+                        Text(
+                            "Searching the local network…",
+                            style = MaterialTheme.typography.bodyMedium,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    }
+                }
+            }
+
             item(span = { GridItemSpan(maxLineSpan) }) {
                 Spacer(Modifier.height(96.dp))
             }

clients/android/app/src/main/kotlin/io/unom/punktfunk/SettingsScreen.kt

@@ -7,6 +7,7 @@ import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ColumnScope
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
@@ -19,6 +20,7 @@ import androidx.compose.material3.ExposedDropdownMenuBox
 import androidx.compose.material3.ExposedDropdownMenuAnchorType
 import androidx.compose.material3.ExposedDropdownMenuDefaults
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedCard
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
@@ -34,8 +36,9 @@ import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
 
 /**
- * Stream settings. Edits are persisted immediately via [onChange]; [onBack] returns to the connect
- * screen. Resolution/refresh "Native" resolve from the device display at connect time.
+ * Stream settings, grouped into Display / Host / Audio / Overlay cards. Edits are persisted
+ * immediately via [onChange]; [onBack] returns to the connect screen. Resolution/refresh "Native"
+ * resolve from the device display at connect time.
  */
 @Composable
 fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -> Unit) {
@@ -48,58 +51,62 @@ fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -
 
     BackHandler(onBack = onBack)
 
+    // Mic uplink — turning it on requests RECORD_AUDIO; if denied, the toggle stays off.
+    val micLauncher = rememberLauncherForActivityResult(
+        ActivityResultContracts.RequestPermission(),
+    ) { granted -> update(s.copy(micEnabled = granted)) }
+
     Column(
-        modifier = Modifier.fillMaxSize().verticalScroll(rememberScrollState()).padding(24.dp),
-        verticalArrangement = Arrangement.spacedBy(16.dp),
+        modifier = Modifier
+            .fillMaxSize()
+            .verticalScroll(rememberScrollState())
+            .padding(horizontal = 20.dp, vertical = 24.dp),
+        verticalArrangement = Arrangement.spacedBy(24.dp),
     ) {
         Text("Settings", style = MaterialTheme.typography.headlineMedium)
 
         val (nw, nh, nhz) = nativeDisplayMode(context)
-        SettingDropdown(
-            label = "Resolution",
-            options = RESOLUTION_OPTIONS.map { (w, h, lbl) ->
-                (w to h) to (if (w == 0) "$lbl ($nw × $nh)" else lbl)
-            },
-            selected = s.width to s.height,
-        ) { (w, h) -> update(s.copy(width = w, height = h)) }
 
-        SettingDropdown(
-            label = "Refresh rate",
-            options = REFRESH_OPTIONS.map { (hz, lbl) -> hz to (if (hz == 0) "$lbl (${nhz} Hz)" else lbl) },
-            selected = s.hz,
-        ) { hz -> update(s.copy(hz = hz)) }
+        SettingsGroup("Display") {
+            SettingDropdown(
+                label = "Resolution",
+                options = RESOLUTION_OPTIONS.map { (w, h, lbl) ->
+                    (w to h) to (if (w == 0) "$lbl ($nw × $nh)" else lbl)
+                },
+                selected = s.width to s.height,
+            ) { (w, h) -> update(s.copy(width = w, height = h)) }
 
-        SettingDropdown(
-            label = "Bitrate",
-            options = BITRATE_OPTIONS,
-            selected = s.bitrateKbps,
-        ) { kbps -> update(s.copy(bitrateKbps = kbps)) }
+            SettingDropdown(
+                label = "Refresh rate",
+                options = REFRESH_OPTIONS.map { (hz, lbl) -> hz to (if (hz == 0) "$lbl ($nhz Hz)" else lbl) },
+                selected = s.hz,
+            ) { hz -> update(s.copy(hz = hz)) }
 
-        SettingDropdown(
-            label = "Compositor (virtual-display host backend)",
-            options = COMPOSITOR_OPTIONS.mapIndexed { i, lbl -> i to lbl },
-            selected = s.compositor,
-        ) { c -> update(s.copy(compositor = c)) }
+            SettingDropdown(
+                label = "Bitrate",
+                options = BITRATE_OPTIONS,
+                selected = s.bitrateKbps,
+            ) { kbps -> update(s.copy(bitrateKbps = kbps)) }
+        }
 
-        SettingDropdown(
-            label = "Controller type",
-            options = GAMEPAD_OPTIONS.mapIndexed { i, lbl -> i to lbl },
-            selected = s.gamepad,
-        ) { g -> update(s.copy(gamepad = g)) }
+        SettingsGroup("Host") {
+            SettingDropdown(
+                label = "Compositor",
+                options = COMPOSITOR_OPTIONS.mapIndexed { i, lbl -> i to lbl },
+                selected = s.compositor,
+            ) { c -> update(s.copy(compositor = c)) }
 
-        // Mic uplink — turning it on requests RECORD_AUDIO; if denied, the toggle stays off.
-        val micLauncher = rememberLauncherForActivityResult(
-            ActivityResultContracts.RequestPermission(),
-        ) { granted -> update(s.copy(micEnabled = granted)) }
-        Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
-            Column(Modifier.weight(1f)) {
-                Text("Microphone", style = MaterialTheme.typography.bodyLarge)
-                Text(
-                    "Send your mic to the host's virtual microphone",
-                    style = MaterialTheme.typography.bodySmall,
-                )
-            }
-            Switch(
+            SettingDropdown(
+                label = "Controller type",
+                options = GAMEPAD_OPTIONS.mapIndexed { i, lbl -> i to lbl },
+                selected = s.gamepad,
+            ) { g -> update(s.copy(gamepad = g)) }
+        }
+
+        SettingsGroup("Audio") {
+            ToggleRow(
+                title = "Microphone",
+                subtitle = "Send your mic to the host's virtual microphone",
                 checked = s.micEnabled,
                 onCheckedChange = { on ->
                     when {
@@ -112,17 +119,10 @@ fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -
             )
         }
 
-        // Live stats overlay (FPS / throughput / capture→client latency). A 3-finger tap in-stream
-        // toggles it without coming back here.
-        Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
-            Column(Modifier.weight(1f)) {
-                Text("Stats overlay", style = MaterialTheme.typography.bodyLarge)
-                Text(
-                    "Show FPS, throughput and latency while streaming (3-finger tap toggles it live)",
-                    style = MaterialTheme.typography.bodySmall,
-                )
-            }
-            Switch(
+        SettingsGroup("Overlay") {
+            ToggleRow(
+                title = "Stats overlay",
+                subtitle = "Show FPS, throughput and latency while streaming (3-finger tap toggles it live)",
                 checked = s.statsHudEnabled,
                 onCheckedChange = { on -> update(s.copy(statsHudEnabled = on)) },
             )
@@ -130,6 +130,47 @@ fun SettingsScreen(initial: Settings, onChange: (Settings) -> Unit, onBack: () -
     }
 }
 
+/** A titled group of settings rendered inside an outlined card. */
+@Composable
+private fun SettingsGroup(title: String, content: @Composable ColumnScope.() -> Unit) {
+    Column(verticalArrangement = Arrangement.spacedBy(10.dp)) {
+        Text(
+            title,
+            style = MaterialTheme.typography.titleSmall,
+            color = MaterialTheme.colorScheme.primary,
+            modifier = Modifier.padding(start = 4.dp),
+        )
+        OutlinedCard(modifier = Modifier.fillMaxWidth()) {
+            Column(
+                modifier = Modifier.padding(16.dp),
+                verticalArrangement = Arrangement.spacedBy(16.dp),
+                content = content,
+            )
+        }
+    }
+}
+
+/** A title + subtitle on the left, a Switch on the right. */
+@Composable
+private fun ToggleRow(
+    title: String,
+    subtitle: String,
+    checked: Boolean,
+    onCheckedChange: (Boolean) -> Unit,
+) {
+    Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.CenterVertically) {
+        Column(Modifier.weight(1f)) {
+            Text(title, style = MaterialTheme.typography.bodyLarge)
+            Text(
+                subtitle,
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        Switch(checked = checked, onCheckedChange = onCheckedChange)
+    }
+}
+
 /** A labelled read-only dropdown over [options] (value → label); calls [onSelect] on a pick. */
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable