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/HUDPlacement.swift

@@ -0,0 +1,35 @@
+// The HUD-corner model persisted by Settings and read wherever the overlay is placed
+// (ContentView, StreamHUDView).
+
+import SwiftUI
+
+/// Which corner the HUD overlay occupies (persisted as `DefaultsKey.hudPlacement`). The raw
+/// values are stable on disk — rename the cases freely, never the strings.
+enum HUDPlacement: String, CaseIterable, Identifiable {
+    case topLeading, topTrailing, bottomLeading, bottomTrailing
+
+    var id: String { rawValue }
+
+    /// SwiftUI overlay alignment for `.overlay(alignment:)`.
+    var alignment: Alignment {
+        switch self {
+        case .topLeading: return .topLeading
+        case .topTrailing: return .topTrailing
+        case .bottomLeading: return .bottomLeading
+        case .bottomTrailing: return .bottomTrailing
+        }
+    }
+
+    /// The HUD's own stack hugs the screen edge it sits against, so its text aligns outward.
+    var isTrailing: Bool { self == .topTrailing || self == .bottomTrailing }
+
+    /// User-facing corner label.
+    var label: String {
+        switch self {
+        case .topLeading: return "Top Left"
+        case .topTrailing: return "Top Right"
+        case .bottomLeading: return "Bottom Left"
+        case .bottomTrailing: return "Bottom Right"
+        }
+    }
+}