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/ServerListView.swift

@@ -0,0 +1,120 @@
+import SwiftUI
+
+struct ServerListView: View {
+    @Environment(AppState.self) private var appState
+    @State private var serverToDelete: SavedServer?
+
+    var body: some View {
+        @Bindable var state = appState
+        NavigationStack {
+            Group {
+                if appState.servers.isEmpty {
+                    ContentUnavailableView(
+                        "No Servers",
+                        systemImage: "server.rack",
+                        description: Text("Tap + to add a server.")
+                    )
+                } else {
+                    List {
+                        ForEach(appState.servers) { server in
+                            Button {
+                                appState.connectTo(server)
+                            } label: {
+                                ServerRowView(server: server)
+                            }
+                            .swipeActions(edge: .trailing) {
+                                Button(role: .destructive) {
+                                    serverToDelete = server
+                                } label: {
+                                    Label("Delete", systemImage: "trash")
+                                }
+                                Button {
+                                    appState.editingServer = server
+                                } label: {
+                                    Label("Edit", systemImage: "pencil")
+                                }
+                                .tint(.blue)
+                            }
+                        }
+                    }
+                }
+            }
+            .navigationTitle("Servers")
+            .toolbar {
+                ToolbarItem(placement: .primaryAction) {
+                    Button {
+                        appState.showAddServer = true
+                    } label: {
+                        Image(systemName: "plus")
+                    }
+                    .accessibilityLabel("Add server")
+                }
+            }
+            .sheet(isPresented: $state.showAddServer) {
+                AddServerView(editing: nil)
+            }
+            .sheet(item: $state.editingServer) { server in
+                AddServerView(editing: server)
+            }
+            .sheet(item: $state.pendingIdentity) { identity in
+                ServerIdentityView(identity: identity)
+            }
+            .sheet(isPresented: $state.showPasswordPrompt) {
+                PasswordPromptView()
+            }
+            .overlay {
+                if appState.isConnecting {
+                    ConnectingOverlay()
+                }
+            }
+            .confirmationDialog("Delete server?", isPresented: Binding(
+                get: { serverToDelete != nil },
+                set: { if !$0 { serverToDelete = nil } }
+            )) {
+                if let s = serverToDelete {
+                    Button("Delete \(s.displayString)", role: .destructive) {
+                        appState.removeServer(s)
+                        serverToDelete = nil
+                    }
+                }
+                Button("Cancel", role: .cancel) { serverToDelete = nil }
+            }
+        }
+    }
+}
+
+private struct ServerRowView: View {
+    let server: SavedServer
+    var body: some View {
+        VStack(alignment: .leading, spacing: 2) {
+            Text(server.displayString)
+                .font(.body)
+            Text(server.authMode == .guest
+                 ? "Guest"
+                 : "Account: \(server.savedUsername)")
+                .font(.caption)
+                .foregroundStyle(.secondary)
+        }
+        .accessibilityElement(children: .combine)
+        .accessibilityLabel("\(server.displayString), \(server.authMode == .guest ? "guest" : "account \(server.savedUsername)")")
+    }
+}
+
+private struct ConnectingOverlay: View {
+    @Environment(AppState.self) private var appState
+    var body: some View {
+        ZStack {
+            Color.black.opacity(0.3).ignoresSafeArea()
+            VStack(spacing: 16) {
+                ProgressView()
+                Text(appState.connectStatus)
+                    .foregroundStyle(.white)
+                Button("Cancel") { appState.cancelConnect() }
+                    .buttonStyle(.bordered)
+                    .tint(.white)
+            }
+            .padding(24)
+            .background(.ultraThinMaterial, in: RoundedRectangle(cornerRadius: 16))
+        }
+    }
+}