feat(ios): ship iOS SwiftUI client (VoiceCatiOS)

Full SwiftUI app at clients/apple/iOS/VoiceCatiOS.xcodeproj:
- 24 Swift source files: AppState + SessionState (@Observable @MainActor),
  AudioSessionManager (AVAudioSession owner + interruption/route handling),
  ServerListStore/SavedServer (App Group container + Keychain sharing),
  and 14 SwiftUI views covering the full feature set
- NavigationSplitView on iPad, TabView on iPhone (horizontalSizeClass)
- Channel tree via OutlineGroup, user list with context menu admin actions
- PTT via DragGesture(minimumDistance: 0) + @GestureState
- onEvent closures hop to MainActor via Task { @MainActor in ... }
- App Group: group.cat.voice.VoiceCat (shared with future ReplayKit extension)

C ABI: add vc_audio_suspend / vc_audio_resume (AudioEngine::suspend/resume)
called by AudioSessionManager on AVAudioSession interruption events.

XCFramework: add ios-arm64 and ios-arm64-simulator slices to build-xcframework.sh;
Package.swift gains .iOS(.v17) platform; CMakePresets.json adds apple-ios /
apple-ios-sim presets with arm64-ios / arm64-ios-simulator vcpkg triplets.

Verified: xcodebuild -target VoiceCatiOS -sdk iphonesimulator26.5 BUILD SUCCEEDED.

clients/apple/iOS/VoiceCatiOS/Views/MoveUserView.swift

@@ -0,0 +1,48 @@
+import SwiftUI
+import VoiceCatCore
+
+struct MoveUserView: View {
+    let user: User
+    @Bindable var session: SessionState
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var selectedChannelId: UInt32 = 0
+
+    var body: some View {
+        NavigationStack {
+            List(session.channels) { channel in
+                HStack {
+                    Text(channel.name)
+                    Spacer()
+                    if channel.id == selectedChannelId {
+                        Image(systemName: "checkmark")
+                            .foregroundStyle(.blue)
+                            .accessibilityHidden(true)
+                    }
+                }
+                .contentShape(Rectangle())
+                .onTapGesture { selectedChannelId = channel.id }
+                .accessibilityElement(children: .combine)
+                .accessibilityLabel("\(channel.name)\(channel.id == selectedChannelId ? ", selected" : "")")
+                .accessibilityAddTraits(channel.id == selectedChannelId ? .isSelected : [])
+            }
+            .navigationTitle("Move \(user.nickname)")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("Cancel") { dismiss() }
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Move") {
+                        session.moveUser(user.id, toChannel: selectedChannelId)
+                        dismiss()
+                    }
+                    .disabled(selectedChannelId == 0)
+                }
+            }
+        }
+        .onAppear {
+            selectedChannelId = user.channelId
+        }
+    }
+}