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/UserListView.swift

@@ -0,0 +1,144 @@
+import SwiftUI
+import VoiceCatCore
+
+struct UserListView: View {
+    @Bindable var session: SessionState
+    @State private var selectedUser: User?
+    @State private var showPerUserTuning = false
+    @State private var showBanUser = false
+    @State private var showMoveUser = false
+    @State private var showPermissions = false
+
+    var body: some View {
+        let channelUsers = session.currentChannelId == 0
+            ? session.users
+            : session.users.filter { $0.channelId == session.currentChannelId }
+
+        List(channelUsers) { user in
+            UserRowView(user: user, isSelf: user.id == session.selfUserId)
+                .contextMenu {
+                    userContextMenu(user: user)
+                }
+        }
+        .listStyle(.plain)
+        .overlay {
+            if channelUsers.isEmpty {
+                ContentUnavailableView(
+                    "No Users",
+                    systemImage: "person.slash",
+                    description: Text(session.currentChannelId == 0 ? "Join a channel to see users." : "No one else here yet.")
+                )
+            }
+        }
+        .sheet(item: $selectedUser) { user in
+            if showPerUserTuning {
+                PerUserTuningView(user: user, session: session)
+            } else if showBanUser {
+                BanUserView(user: user, session: session)
+            } else if showMoveUser {
+                MoveUserView(user: user, session: session)
+            } else if showPermissions {
+                PermissionsView(user: user, session: session)
+            }
+        }
+    }
+
+    @ViewBuilder
+    private func userContextMenu(user: User) -> some View {
+        if user.id != session.selfUserId {
+            Button {
+                selectedUser = user
+                showPerUserTuning = true
+                showBanUser = false; showMoveUser = false; showPermissions = false
+            } label: {
+                Label("Volume / NR", systemImage: "speaker.wave.2")
+            }
+            if session.permissions.canKick || session.permissions.isAdmin {
+                Divider()
+                Button {
+                    session.kickUser(user.id, reason: "")
+                } label: {
+                    Label("Kick", systemImage: "person.fill.xmark")
+                }
+                if session.permissions.canBan || session.permissions.isAdmin {
+                    Button(role: .destructive) {
+                        selectedUser = user
+                        showBanUser = true
+                        showPerUserTuning = false; showMoveUser = false; showPermissions = false
+                    } label: {
+                        Label("Ban…", systemImage: "nosign")
+                    }
+                }
+            }
+            if session.permissions.canMoveUsers || session.permissions.isAdmin {
+                Button {
+                    selectedUser = user
+                    showMoveUser = true
+                    showPerUserTuning = false; showBanUser = false; showPermissions = false
+                } label: {
+                    Label("Move to channel…", systemImage: "arrow.right.circle")
+                }
+            }
+            if session.permissions.isAdmin {
+                Divider()
+                let muted = user.serverMuted
+                Button {
+                    session.setServerMute(user.id, muted: !muted, deafened: user.serverDeafened)
+                } label: {
+                    Label(muted ? "Unmute" : "Server Mute", systemImage: muted ? "mic" : "mic.slash")
+                }
+                Button {
+                    selectedUser = user
+                    showPermissions = true
+                    showPerUserTuning = false; showBanUser = false; showMoveUser = false
+                } label: {
+                    Label("Permissions…", systemImage: "lock.shield")
+                }
+            }
+        }
+    }
+}
+
+private struct UserRowView: View {
+    let user: User
+    let isSelf: Bool
+
+    var body: some View {
+        HStack(spacing: 10) {
+            Image(systemName: user.selfMicMuted || user.serverMuted ? "mic.slash.fill" : "mic.fill")
+                .foregroundStyle(user.selfMicMuted || user.serverMuted ? .red : .green)
+                .imageScale(.small)
+                .accessibilityHidden(true)
+            VStack(alignment: .leading, spacing: 1) {
+                HStack(spacing: 4) {
+                    Text(user.nickname)
+                        .fontWeight(isSelf ? .semibold : .regular)
+                    if isSelf {
+                        Text("(you)")
+                            .font(.caption2)
+                            .foregroundStyle(.secondary)
+                    }
+                    if user.isGuest {
+                        Text("guest")
+                            .font(.caption2)
+                            .foregroundStyle(.secondary)
+                    }
+                }
+                if user.serverMuted || user.serverDeafened {
+                    Text(user.serverDeafened ? "server deafened" : "server muted")
+                        .font(.caption2)
+                        .foregroundStyle(.orange)
+                }
+            }
+            Spacer()
+            if user.selfDeafened {
+                Image(systemName: "headphones.slash")
+                    .imageScale(.small)
+                    .foregroundStyle(.secondary)
+                    .accessibilityHidden(true)
+            }
+        }
+        .accessibilityElement(children: .combine)
+        .accessibilityLabel("\(user.nickname)\(isSelf ? ", you" : "")\(user.isGuest ? ", guest" : "")\(user.selfMicMuted ? ", muted" : "")\(user.serverMuted ? ", server muted" : "")")
+    }
+}