feat(wsService, WebRTCManager): enhance call handling with media type support and negotiation improvements

- Added optional media_type to WSCallIncomingMessage for better call type differentiation.
- Updated call_type assignment in WebSocketService to prioritize media_type if available.
- Removed initialOfferCreated flag in WebRTCManager to simplify negotiation logic.
- Improved negotiation handling by releasing the negotiation lock after offer creation, ensuring smoother call setup.

src/services/wsService.ts

@@ -48,6 +48,7 @@ export interface WSCallIncomingMessage {
   conversation_id: string;
   caller_id: string;
   call_type: string;
+  media_type?: string;
   created_at: number;
   lifetime?: number;
   ice_servers?: ICEServerConfig[];
@@ -621,7 +622,7 @@ class WebSocketService {
       call_id: payload.call_id,
       conversation_id: payload.conversation_id,
       caller_id: payload.caller_id,
-      call_type: payload.call_type,
+      call_type: payload.media_type || payload.call_type,
       created_at: payload.created_at,
       lifetime: payload.lifetime,
       ice_servers: payload.ice_servers,