feat: LiveKit voice session, control channel, transcripts (Phase 2)

- VoiceSession: token->connect with fresh-room retry on timeout, agent
  discovery, agent_ready wait, mic enable/mute, text send over lk.chat
- ControlChannel: outbound set_voice/set_model/get_models/set_mode/
  media_state; inbound agent_ready/models/model_changed/task_event
- TranscriptHandler: transcription segments + transcript topic finals,
  partial/final dedupe per role
- ConversationView/OrbView: status orb, mic/text-mode toggles, composer
- ServerConfig: plain ws:// signaling for private IPs (self-signed TLS
  not injectable into SDK WebSocket); Info.plist local networking

Sources/App/VoiceApp.swift

@@ -1,9 +1,14 @@
 import SwiftUI
+import LiveKit
 
 @main
 struct VoiceApp: App {
     @StateObject private var settings = SettingsStore()
 
+    init() {
+        LiveKitSDK.setLogLevel(.debug)
+    }
+
     var body: some Scene {
         WindowGroup {
             ConversationView(settings: settings)