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/Gamepad/GamepadWire.swift

@@ -0,0 +1,62 @@
+// The gamepad wire contract shared by capture (GamepadCapture), feedback (GamepadFeedback),
+// and the tests — button bits, axis ids, and the touchpad/motion unit conversions.
+
+import Foundation
+
+/// The gamepad wire contract (mirrors `punktfunk_core::input::gamepad`).
+public enum GamepadWire {
+    public static let dpadUp: UInt32 = 0x0001
+    public static let dpadDown: UInt32 = 0x0002
+    public static let dpadLeft: UInt32 = 0x0004
+    public static let dpadRight: UInt32 = 0x0008
+    public static let start: UInt32 = 0x0010
+    public static let back: UInt32 = 0x0020
+    public static let leftStickClick: UInt32 = 0x0040
+    public static let rightStickClick: UInt32 = 0x0080
+    public static let leftShoulder: UInt32 = 0x0100
+    public static let rightShoulder: UInt32 = 0x0200
+    public static let guide: UInt32 = 0x0400
+    public static let a: UInt32 = 0x1000
+    public static let b: UInt32 = 0x2000
+    public static let x: UInt32 = 0x4000
+    public static let y: UInt32 = 0x8000
+    /// DualSense touchpad click (Moonlight's extended-button bit position).
+    public static let touchpadClick: UInt32 = 0x10_0000
+
+    public static let allButtons: [UInt32] = [
+        dpadUp, dpadDown, dpadLeft, dpadRight, start, back,
+        leftStickClick, rightStickClick, leftShoulder, rightShoulder, guide,
+        a, b, x, y, touchpadClick,
+    ]
+
+    public static let axisLSX: UInt32 = 0
+    public static let axisLSY: UInt32 = 1
+    public static let axisRSX: UInt32 = 2
+    public static let axisRSY: UInt32 = 3
+    public static let axisLT: UInt32 = 4
+    public static let axisRT: UInt32 = 5
+
+    /// Raw DualSense gyro units per rad/s: hid-playstation's calibration over the host's
+    /// fixed blob resolves to 20 LSB per deg/s.
+    public static let gyroLSBPerRadS: Float = 20 * 180 / .pi
+    /// Raw DualSense accelerometer units per g (same derivation).
+    public static let accelLSBPerG: Float = 10_000
+
+    /// GC touchpad coordinates (±1, +y up) → wire (0...65535, origin top-left, +y down).
+    public static func touchpad(x: Float, y: Float) -> (x: UInt16, y: UInt16) {
+        let wx = ((x.clamped(to: -1...1) + 1) / 2 * 65535).rounded()
+        let wy = ((1 - y.clamped(to: -1...1)) / 2 * 65535).rounded()
+        return (UInt16(wx), UInt16(wy))
+    }
+
+    /// Scale + clamp one motion component into the raw signed-16 sensor domain.
+    public static func motionRaw(_ value: Float, scale: Float) -> Int16 {
+        Int16((value * scale).rounded().clamped(to: Float(Int16.min)...Float(Int16.max)))
+    }
+}
+
+extension Float {
+    fileprivate func clamped(to range: ClosedRange<Float>) -> Float {
+        Swift.min(Swift.max(self, range.lowerBound), range.upperBound)
+    }
+}