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/PunktfunkKit/Video/Probe444Blobs.swift

@@ -0,0 +1,36 @@
+// Synthetic 4:4:4 HEVC keyframes used only by `Stage444Probe` to probe decode capability.
+//
+// Each is the first IDR access unit (VPS + SPS + PPS + IDR slice, Annex-B) of a 256×256 HEVC
+// Range-Extensions clip — `chroma_format_idc = 3` — generated offline with libx265:
+//   ffmpeg -f lavfi -i color=c=gray:s=256x256:r=30:d=0.1 -frames:v 3 \
+//          -pix_fmt yuv444p[10le] -c:v libx265 \
+//          -x265-params keyint=1:min-keyint=1:no-info=1:repeat-headers=1:aud=0 -f hevc out.hevc
+// 256×256 clears the hardware decoder's minimum-dimension floor (a 16×16 clip is rejected for every
+// chroma format). Validated to hardware-decode to `444v`/`x444` on Apple Silicon (M3).
+enum Probe444Blobs {
+    /// 256×256 HEVC Range-Extensions 4:4:4 keyframe (Annex-B): 134 bytes.
+    static let au444_8bit: [UInt8] = [
+        0x00, 0x00, 0x00, 0x01, 0x40, 0x01, 0x0c, 0x01, 0xff, 0xff, 0x04, 0x08, 0x00, 0x00, 0x03, 0x00,
+        0x9e, 0x28, 0x00, 0x00, 0x03, 0x00, 0x00, 0x3c, 0xba, 0x02, 0x40, 0x00, 0x00, 0x00, 0x01, 0x42,
+        0x01, 0x01, 0x04, 0x08, 0x00, 0x00, 0x03, 0x00, 0x9e, 0x28, 0x00, 0x00, 0x03, 0x00, 0x00, 0x3c,
+        0x90, 0x01, 0x01, 0x00, 0x80, 0xb2, 0xdd, 0x49, 0x26, 0x57, 0x80, 0xb4, 0x04, 0x00, 0x00, 0x03,
+        0x00, 0x04, 0x00, 0x00, 0x03, 0x00, 0x78, 0x20, 0x00, 0x00, 0x00, 0x01, 0x44, 0x01, 0xc1, 0x72,
+        0x86, 0x0c, 0x06, 0x24, 0x00, 0x00, 0x00, 0x01, 0x28, 0x01, 0xaf, 0x72, 0x15, 0xe8, 0x34, 0xeb,
+        0xae, 0xfb, 0xfe, 0x75, 0x57, 0xca, 0xc1, 0x71, 0x43, 0x16, 0xf5, 0xc2, 0x40, 0xbd, 0x80, 0xa6,
+        0x65, 0x35, 0x20, 0x28, 0x81, 0xa2, 0x5e, 0xc0, 0x93, 0x04, 0x10, 0x9b, 0x00, 0x34, 0xe0, 0x87,
+        0x00, 0x00, 0x03, 0x00, 0x5b, 0x40,
+    ]
+
+    /// 256×256 HEVC Range-Extensions 4:4:4 10-bit keyframe (Annex-B): 133 bytes.
+    static let au444_10bit: [UInt8] = [
+        0x00, 0x00, 0x00, 0x01, 0x40, 0x01, 0x0c, 0x01, 0xff, 0xff, 0x04, 0x08, 0x00, 0x00, 0x03, 0x00,
+        0x9c, 0x28, 0x00, 0x00, 0x03, 0x00, 0x00, 0x3c, 0xba, 0x02, 0x40, 0x00, 0x00, 0x00, 0x01, 0x42,
+        0x01, 0x01, 0x04, 0x08, 0x00, 0x00, 0x03, 0x00, 0x9c, 0x28, 0x00, 0x00, 0x03, 0x00, 0x00, 0x3c,
+        0x90, 0x01, 0x01, 0x00, 0x80, 0x9b, 0x2d, 0xd4, 0x92, 0x65, 0x78, 0x0b, 0x40, 0x40, 0x00, 0x00,
+        0x03, 0x00, 0x40, 0x00, 0x00, 0x07, 0x82, 0x00, 0x00, 0x00, 0x01, 0x44, 0x01, 0xc1, 0x72, 0x86,
+        0x0c, 0x06, 0x24, 0x00, 0x00, 0x00, 0x01, 0x28, 0x01, 0xaf, 0x72, 0x15, 0xe8, 0x34, 0xeb, 0xae,
+        0xfb, 0xfe, 0x75, 0x57, 0xca, 0xc1, 0x71, 0x43, 0x16, 0xf5, 0xc2, 0x40, 0xbd, 0x80, 0xa6, 0x65,
+        0x35, 0x20, 0x28, 0x81, 0xa2, 0x5e, 0xc0, 0x93, 0x04, 0x10, 0x9b, 0x00, 0x34, 0xe0, 0x87, 0x00,
+        0x00, 0x03, 0x00, 0x5b, 0x40,
+    ]
+}