feat(apple): gamepad UI v2 — controller settings + add host, aurora, macOS

Sources reorganized (client: Home/Session/Settings/Stores/Support/Trust; kit:
Audio/Connection/Gamepad/Input/Support/Video/Views) with the big files split
along the same seams.

The gamepad mode is couch-complete, and now on macOS too (the living-room
Mac case), not just iOS/iPadOS:

- GamepadSettingsView: a console-style, fully controller-navigable settings
  screen (X from the launcher) — up/down moves focus, left/right steps values
  (clamped, boundary thud), A cycles/toggles, B closes; the focused row shows a
  one-line description. Backed by GamepadMenuList, the vertical sibling of
  GamepadCarousel, and SettingsOptions — the option lists hoisted out of
  SettingsView statics and shared by the touch, tvOS and gamepad settings.
- GamepadAddHostView + GamepadKeyboard: register a host end to end with a pad
  — field rows open an on-screen controller keyboard (dpad grid, A types,
  X backspaces, B done); the launcher carousel ends in an Add Host tile, so
  the dead-end "add one with touch first" empty state is gone.
- Launcher polish: contextual hint bar with the pad's real button glyphs,
  controller name + battery chip, one shared console chrome.
- GamepadScreenBackground: an animated aurora (TimelineView-driven drifting
  blobs in the brand's violet family, breathing radii, slow hue shift,
  legibility scrim; freezes under Reduce Motion). Pure SwiftUI on purpose — a
  .metal library only bundles reliably in one of the two build systems (SPM vs
  the xcodeproj's synced folders) these sources compile under.
- macOS port: settings/add-host/library present as sized sheets (a macOS sheet
  takes its content's IDEAL size, and the GeometryReader-driven screens
  collapsed to nothing), NSScreen-based mode lists, scroll indicators .never
  (the "always show scroll bars" setting overrides .hidden), tray scrims so
  scrolled rows dim under the pinned title/hints, extra title clearance, and a
  PUNKTFUNK_FORCE_GAMEPAD_UI=1 dev hook — launcher/settings/add-host/keyboard/
  library render-verified live on a real Mac + LAN hosts.
- GamepadMenuInput: X button support, and (re)start now snapshots held buttons
  so a controller handoff press never fires twice (the B that closed the
  keyboard no longer also cancels the screen underneath).
- Cleanups: one "Connection failed" alert in ContentView instead of one per
  home screen; HostDiscovery.advertises/unsaved shared by both home screens.
- host: can_encode_444 stub for the non-Linux/Windows host build (the macOS
  synthetic-source loopback used by the Swift tests).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/Sources/PunktfunkClient/ContentView.swift

@@ -55,9 +55,9 @@ struct ContentView: View {
     #if !os(macOS)
     @State private var showSettings = false
     #endif
-    #if os(iOS)
+    #if os(iOS) || os(macOS)
     // A connected controller (+ the Settings toggle) swaps the whole home screen for
-    // GamepadHomeView instead of retrofitting HomeView's touch UI — see `home` below.
+    // GamepadHomeView instead of retrofitting HomeView's touch/desktop UI — see `home` below.
     @ObservedObject private var gamepadManager = GamepadManager.shared
     @AppStorage(DefaultsKey.gamepadUIEnabled) private var gamepadUIEnabled = true
     private var gamepadUIActive: Bool {
@@ -137,12 +137,16 @@ struct ContentView: View {
         // The library is a full-screen presentation, not a sheet: on iPad a sheet is a centered page
         // card, but the gamepad coverflow is meant to be an immersive, full-bleed screen (and the
         // launcher behind it stops consuming the controller — see GamepadHomeView's `isActive`).
-        // macOS has no `fullScreenCover`, so it keeps the sheet there.
+        // macOS has no `fullScreenCover`, so it keeps the sheet there — with an explicit size: a
+        // macOS sheet takes its content's IDEAL size, and both library layouts are geometry-driven
+        // (the coverflow is a GeometryReader, ideal ≈ zero), so without a frame it collapses to a
+        // tiny panel.
         #if os(macOS)
         .sheet(item: $libraryTarget) { host in
             NavigationStack {
                 LibraryView(store: store, host: host, onLaunch: { launchTitle(host, $0) })
             }
+            .frame(minWidth: 940, minHeight: 620)
         }
         #else
         .fullScreenCover(item: $libraryTarget) { host in
@@ -176,6 +180,18 @@ struct ContentView: View {
                 + "device in the host's web console (port 3000 → Pairing) — no PIN needed. Or "
                 + "pair with the 4-digit PIN it can display.")
         }
+        // One "Connection failed" surface for every home screen (touch grid, gamepad launcher) and
+        // platform — SessionModel funnels all connect/session errors into `errorMessage`.
+        .alert(
+            "Connection failed",
+            isPresented: Binding(
+                get: { model.errorMessage != nil },
+                set: { if !$0 { model.errorMessage = nil } })
+        ) {
+            Button("OK", role: .cancel) {}
+        } message: {
+            Text(model.errorMessage ?? "")
+        }
         // The delegated-approval wait: the host holds the connection open until the operator
         // approves it. Cancel returns the UI at once; the in-flight connect is left to time out
         // and its late result is discarded by SessionModel's connect guard (disconnect resets the
@@ -197,12 +213,21 @@ struct ContentView: View {
 
     private var home: some View {
         #if os(macOS)
-        HomeView(
-            store: store, model: model, discovery: discovery,
-            showAddHost: $showAddHost, pairingTarget: $pairingTarget,
-            speedTestTarget: $speedTestTarget, libraryTarget: $libraryTarget,
-            connect: { connect($0) }, connectDiscovered: connectDiscovered,
-            onPaired: handlePaired, onLaunchTitle: launchTitle)
+        Group {
+            if gamepadUIActive {
+                GamepadHomeView(
+                    store: store, model: model, discovery: discovery,
+                    libraryTarget: $libraryTarget,
+                    connect: { connect($0) }, connectDiscovered: connectDiscovered)
+            } else {
+                HomeView(
+                    store: store, model: model, discovery: discovery,
+                    showAddHost: $showAddHost, pairingTarget: $pairingTarget,
+                    speedTestTarget: $speedTestTarget, libraryTarget: $libraryTarget,
+                    connect: { connect($0) }, connectDiscovered: connectDiscovered,
+                    onPaired: handlePaired, onLaunchTitle: launchTitle)
+            }
+        }
         #elseif os(iOS)
         Group {
             if gamepadUIActive {
@@ -308,7 +333,8 @@ struct ContentView: View {
                     onSessionEnd: { [weak model] in
                         Task { @MainActor in model?.sessionEnded() }
                     },
-                    presentMeter: model.presentLatency
+                    presentMeter: model.presentLatency,
+                    presentTailMeter: model.presentTail
                 )
                 .overlay(alignment: placement.alignment) {
                     if captureEnabled && hudEnabled {
@@ -565,23 +591,3 @@ private struct ApprovalRequest {
     let host: StoredHost
     let advertisedFingerprint: Data?
 }
-
-private extension Data {
-    /// Parse an even-length hex string into bytes; nil on any non-hex character or odd length.
-    /// Used to turn an mDNS-advertised cert fingerprint into a connect pin.
-    init?(hexString: String) {
-        let chars = Array(hexString)
-        guard chars.count.isMultiple(of: 2) else { return nil }
-        var bytes = [UInt8]()
-        bytes.reserveCapacity(chars.count / 2)
-        var i = 0
-        while i < chars.count {
-            guard let hi = chars[i].hexDigitValue, let lo = chars[i + 1].hexDigitValue else {
-                return nil
-            }
-            bytes.append(UInt8(hi << 4 | lo))
-            i += 2
-        }
-        self = Data(bytes)
-    }
-}