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/Support/GlassStyle.swift

@@ -0,0 +1,69 @@
+// GlassStyle.swift — the app's single, availability-gated entry point to Apple's "Liquid
+// Glass" (iOS / macOS / tvOS 26). Every Liquid Glass symbol (glassEffect, Glass, the
+// .glassProminent button style …) is HARD-gated to OS 26: referencing one with our
+// deployment targets (macOS 14 / iOS 17 / tvOS 17) is a COMPILE error, not a silent no-op,
+// unless it sits behind `if #available`. So all glass in the app routes through the two
+// helpers below, each of which falls back to the EXACT look the app shipped before
+// (.regularMaterial / .borderedProminent) — nothing regresses on older OSes, and the gating
+// lives in exactly one file.
+
+import SwiftUI
+
+// MARK: - Glass background
+
+/// Liquid Glass behind a floating / overlay surface, with the pre-26 `.regularMaterial`
+/// look as the fallback. Use ONLY on the floating control / overlay layer (the streaming
+/// HUD, the trust card, the touch exit chip) — never on content tiles or dense forms (HIG).
+///
+/// `glassEffect()`'s own default shape is a Capsule, so panels MUST pass an explicit shape
+/// (a RoundedRectangle / Circle) or they render as a pill. `interactive` makes the glass
+/// react to press — only meaningful when the glass itself is the tap target.
+private struct GlassBackground<S: Shape>: ViewModifier {
+    let shape: S
+    var interactive = false
+
+    func body(content: Content) -> some View {
+        if #available(iOS 26, macOS 26, tvOS 26, *) {
+            content.glassEffect(interactive ? .regular.interactive() : .regular, in: shape)
+        } else {
+            content.background(.regularMaterial, in: shape)
+        }
+    }
+}
+
+extension View {
+    /// Liquid Glass (26+) or the existing `.regularMaterial` (pre-26) behind a floating
+    /// surface. Pass the surface's shape explicitly — glass defaults to a Capsule otherwise.
+    func glassBackground<S: Shape>(_ shape: S, interactive: Bool = false) -> some View {
+        modifier(GlassBackground(shape: shape, interactive: interactive))
+    }
+}
+
+// MARK: - Glass primary button
+
+/// The single prominent action on a floating / overlay or sheet surface: the Liquid-Glass
+/// prominent button style on 26+, falling back to `.borderedProminent` (the app's current
+/// primary style) below. Apply directly to a `Button`; role / keyboardShortcut / disabled
+/// chain after it as usual. tvOS stays `.borderedProminent` always — glass chrome fights the
+/// focus engine, and keeping it preserves today's tvOS look exactly.
+private struct GlassProminentButton: ViewModifier {
+    func body(content: Content) -> some View {
+        #if os(tvOS)
+        content.buttonStyle(.borderedProminent)
+        #else
+        if #available(iOS 26, macOS 26, *) {
+            content.buttonStyle(.glassProminent)
+        } else {
+            content.buttonStyle(.borderedProminent)
+        }
+        #endif
+    }
+}
+
+extension View {
+    /// Liquid-Glass prominent style (26+, non-tvOS) or `.borderedProminent`. Drop-in for the
+    /// `.buttonStyle(.borderedProminent)` on a surface's primary action.
+    func glassProminentButtonStyle() -> some View {
+        modifier(GlassProminentButton())
+    }
+}