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/Settings/SettingsCategory.swift

@@ -0,0 +1,60 @@
+// SettingsView's navigation and presentation helpers: the iOS settings categories, the iPad
+// sheet sizing, and the bounded-slider clamp.
+
+import SwiftUI
+
+#if os(iOS)
+/// The settings groups, mirroring the macOS preference tabs. On iPad each is a sidebar row that
+/// drives the detail pane; on iPhone the same list collapses to pushed sub-pages. Internal (not
+/// private) so the screenshot harness can open SettingsView on a specific category.
+enum SettingsCategory: String, CaseIterable, Identifiable {
+    case general, display, audio, controllers, advanced, about
+
+    var id: Self { self }
+
+    var title: String {
+        switch self {
+        case .general: return "General"
+        case .display: return "Display"
+        case .audio: return "Audio"
+        case .controllers: return "Controllers"
+        case .advanced: return "Advanced"
+        case .about: return "About"
+        }
+    }
+
+    var symbol: String {
+        switch self {
+        case .general: return "gearshape"
+        case .display: return "display"
+        case .audio: return "speaker.wave.2"
+        case .controllers: return "gamecontroller"
+        case .advanced: return "slider.horizontal.3"
+        case .about: return "info.circle"
+        }
+    }
+}
+
+extension View {
+    /// Present the settings sheet large on iPad so the NavigationSplitView has room for its
+    /// sidebar + detail — a default form sheet is too narrow and the split view would collapse to
+    /// the iPhone push list. No-op on iPhone (the standard sheet is already right) and on iOS 17
+    /// (no `presentationSizing` — it falls back to the default sheet, which still degrades cleanly
+    /// to the push list).
+    @ViewBuilder
+    func settingsSheetSizing() -> some View {
+        if UIDevice.current.userInterfaceIdiom == .pad, #available(iOS 18, *) {
+            presentationSizing(.page)
+        } else {
+            self
+        }
+    }
+}
+#endif
+
+extension Double {
+    /// The log-scale slider mapping needs a bounded input (Automatic stores 0).
+    func clamped(_ lo: Double, _ hi: Double) -> Double {
+        Swift.min(Swift.max(self, lo), hi)
+    }
+}