feat(apple): iOS/iPadOS client — touch, pointer lock, shared SwiftUI shell

The whole client now runs on iPadOS/iOS from the same sources, first-lit live in the
iPad simulator against the real host at 1280x720@60 (60 fps on the HUD, capture state
machine active, mic permission flow shown).

- PunktfunkCore.xcframework grows iOS device + universal-simulator slices
  (BUILD_IOS=1; rustup targets aarch64-apple-ios{,-sim} + x86_64-apple-ios).
- The decode pump is extracted into a shared StreamPump (identical IDR re-gate logic on
  both platforms); the iOS StreamView (StreamViewIOS.swift) has the same name/signature
  as the macOS one, so ContentView & co. are byte-identical across platforms — hosted
  in a UIViewController for prefersPointerLocked (the iPadOS cursor capture; see README
  note 9 for the UIHostingController forwarding caveat).
- Touch is always forwarded: per-finger wire ids, coordinates mapped through the
  aspect-fit letterbox into LIVE host-mode pixels (surface == host mode, identity
  rescale host-side; follows mid-stream requestMode switches).
- InputCapture is cross-platform: GC works the same on iPadOS, ⌘⎋ is detected from the
  HID stream there; stale-⌘ tracking after focus loss fixed on both platforms
  (releaseAll now drops the modifier/latch state — a ⌘ released in another app
  otherwise hijacked Esc forever).
- SessionAudio: AVAudioSession on iOS (.playAndRecord + .defaultToSpeaker — without it
  iPhones route host audio to the EARPIECE; deactivated with
  notifyOthersOnDeactivation on stop so interrupted background audio resumes); HAL
  device pinning + the Settings pickers stay macOS-only.
- New Punktfunk-iOS app target (shared synchronized sources, generated Info.plist with
  mic + local-network usage descriptions — QUIC to a LAN host trips local network
  privacy on real devices — scene manifest + indirect input events for Stage Manager /
  external displays), shared scheme, macOS min-window frames gated off iOS.

For the iPad-on-an-external-screen idea: with multiple scenes + indirect input enabled,
Stage Manager iPads can drag the punktfunk window onto the external display and drive
the PC with keyboard/mouse/touch. Known gaps (README note 9): the pointer-lock
preference isn't consulted through UIHostingController (relative mouse works, the local
cursor just stays visible) and AVAudioSession interruptions don't auto-restart audio.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/Sources/PunktfunkClient/SettingsView.swift

@@ -2,7 +2,9 @@
 // virtual output at exactly this size/refresh — there is no scaling anywhere in the
 // pipeline.
 
+#if os(macOS)
 import AppKit
+#endif
 import PunktfunkKit
 import SwiftUI
 
@@ -11,11 +13,13 @@ struct SettingsView: View {
     @AppStorage("punktfunk.height") private var height = 1080
     @AppStorage("punktfunk.hz") private var hz = 60
     @AppStorage("punktfunk.compositor") private var compositor = 0
+    @AppStorage("punktfunk.micEnabled") private var micEnabled = true
+    #if os(macOS)
     @AppStorage("punktfunk.speakerUID") private var speakerUID = ""
     @AppStorage("punktfunk.micUID") private var micUID = ""
-    @AppStorage("punktfunk.micEnabled") private var micEnabled = true
     @State private var outputDevices: [AudioDevice] = []
     @State private var inputDevices: [AudioDevice] = []
+    #endif
 
     var body: some View {
         Form {
@@ -39,6 +43,7 @@ struct SettingsView: View {
                     .foregroundStyle(.secondary)
             }
             Section {
+                #if os(macOS)
                 Picker("Speaker", selection: $speakerUID) {
                     Text("System default").tag("")
                     ForEach(outputDevices) { device in
@@ -49,7 +54,9 @@ struct SettingsView: View {
                         Text("Unavailable device").tag(speakerUID)
                     }
                 }
+                #endif
                 Toggle("Send microphone to the host", isOn: $micEnabled)
+                #if os(macOS)
                 Picker("Microphone", selection: $micUID) {
                     Text("System default").tag("")
                     ForEach(inputDevices) { device in
@@ -61,6 +68,7 @@ struct SettingsView: View {
                     }
                 }
                 .disabled(!micEnabled)
+                #endif
             } header: {
                 Text("Audio")
             } footer: {
@@ -89,19 +97,29 @@ struct SettingsView: View {
             }
         }
         .formStyle(.grouped)
+        #if os(macOS)
         .frame(width: 380)
         .fixedSize()
         .onAppear {
             outputDevices = AudioDevices.outputs()
             inputDevices = AudioDevices.inputs()
         }
+        #endif
     }
 
     private func fillFromMainScreen() {
+        #if os(macOS)
         guard let screen = NSScreen.main else { return }
         let scale = screen.backingScaleFactor
         width = Int(screen.frame.width * scale)
         height = Int(screen.frame.height * scale)
         hz = screen.maximumFramesPerSecond
+        #else
+        // nativeBounds is portrait-oriented pixels — streams are landscape.
+        let bounds = UIScreen.main.nativeBounds
+        width = Int(max(bounds.width, bounds.height))
+        height = Int(min(bounds.width, bounds.height))
+        hz = UIScreen.main.maximumFramesPerSecond
+        #endif
     }
 }