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/Networking/TokenClient.swift

@@ -43,9 +43,9 @@ final class TokenClient {
     let config: ServerConfig
     private let session: URLSession
 
-    init(config: ServerConfig, session: URLSession = .shared) {
+    init(config: ServerConfig) {
         self.config = config
-        self.session = session
+        self.session = TLSPinning.session()
     }
 
     func fetchToken() async throws -> TokenResponse {