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/Session/StreamHUDView.swift

@@ -0,0 +1,78 @@
+// The streaming overlay HUD: mode + fps/throughput, the capture→client (and, under the stage-2
+// presenter, capture→present) latency lines, the platform input hint, and disconnect.
+
+import PunktfunkKit
+import SwiftUI
+
+struct StreamHUDView: View {
+    @ObservedObject var model: SessionModel
+    let connection: PunktfunkConnection
+    var placement: HUDPlacement = .topTrailing
+
+    var body: some View {
+        VStack(alignment: placement.isTrailing ? .trailing : .leading, spacing: 4) {
+            HStack(spacing: 6) {
+                Circle()
+                    .fill(Color.accentColor)
+                    .frame(width: 7, height: 7)
+                Text("\(connection.width)×\(connection.height)@\(connection.refreshHz)  \(model.fps) fps  \(model.mbps, specifier: "%.1f") Mb/s")
+                    .font(.system(.caption, design: .monospaced))
+            }
+            if model.latencyValid {
+                // Capture→client-receipt (skew-corrected); excludes the layer's decode+present —
+                // see LatencyMeter. "(same-host)" when the host didn't answer the skew handshake.
+                Text("capture→client \(model.latencyP50Ms, specifier: "%.1f")/\(model.latencyP95Ms, specifier: "%.1f") ms p50/p95\(model.latencySkewCorrected ? "" : " (same-host)")")
+                    .font(.system(.caption2, design: .monospaced))
+                    .foregroundStyle(.secondary)
+            }
+            if model.presentLatencyValid {
+                // Capture→present (glass-to-glass, modulo host render→capture) — stage-2 presenter
+                // only; stage-1's layer presents internally with no per-frame stamp.
+                Text("capture→present \(model.presentLatencyP50Ms, specifier: "%.1f")/\(model.presentLatencyP95Ms, specifier: "%.1f") ms p50/p95\(model.presentLatencySkewCorrected ? "" : " (same-host)")")
+                    .font(.system(.caption2, design: .monospaced))
+                    .foregroundStyle(.secondary)
+            }
+            if model.presentTailValid {
+                // Decode→present (the client-local "present tail": ring wait + render + vsync) —
+                // the term the stage-2 presenter shortens; no skew applies (one clock).
+                Text("decode→present \(model.presentTailP50Ms, specifier: "%.1f")/\(model.presentTailP95Ms, specifier: "%.1f") ms p50/p95")
+                    .font(.system(.caption2, design: .monospaced))
+                    .foregroundStyle(.secondary)
+            }
+            // While captured the cursor is hidden+frozen, so the button is keyboard-only
+            // (⌘⎋ or Cmd+Tab release the cursor; released, it's clickable again).
+            #if os(macOS)
+            Text(model.mouseCaptured
+                ? "⌘⎋ releases the mouse"
+                : "Click the stream to capture input")
+                .font(.geist(11, relativeTo: .caption2))
+                .foregroundStyle(.secondary)
+            #elseif os(iOS)
+            // Touch always plays directly; ⌘⎋ (hardware keyboard) toggles kb/mouse.
+            Text(model.mouseCaptured
+                ? "⌘⎋ releases keyboard & mouse"
+                : "⌘⎋ captures keyboard & mouse")
+                .font(.geist(11, relativeTo: .caption2))
+                .foregroundStyle(.secondary)
+            #endif
+            #if os(tvOS)
+            // No focusable control during play: a focusable button steals the controller's
+            // A press (the focus engine consumes it before the host sees it). Disconnect is
+            // the Siri Remote's Menu button (.onExitCommand on the stream) — just hint it.
+            Text("Press Menu to disconnect")
+                .font(.geist(12, relativeTo: .caption))
+                .foregroundStyle(.secondary)
+            #else
+            // ⌘D lives on the app's Stream menu (so it still works when the HUD is hidden);
+            // this button is the in-overlay, click-to-disconnect affordance.
+            Button("Disconnect (⌘D)") { model.disconnect() }
+                .font(.geist(12, relativeTo: .caption))
+            #endif
+        }
+        .padding(10)
+        // Floating HUD over live video — the canonical Liquid-Glass overlay surface (26+);
+        // falls back to .regularMaterial below 26 (see GlassStyle).
+        .glassBackground(RoundedRectangle(cornerRadius: 10))
+        .padding(10)
+    }
+}