feat(proxy-engine,webrtc): add B2BUA SIP leg handling and WebRTC call bridging for outbound calls

ts/frontend.ts

@@ -339,11 +339,13 @@ export function initWebUi(
   onHangupCall: (callId: string) => boolean,
   onConfigSaved?: () => void,
   callManager?: CallManager,
+  voiceboxManager?: VoiceboxManager,
   /** WebRTC signaling handlers — forwarded to Rust proxy-engine. */
   onWebRtcOffer?: (sessionId: string, sdp: string, ws: WebSocket) => Promise<void>,
   onWebRtcIce?: (sessionId: string, candidate: any) => Promise<void>,
   onWebRtcClose?: (sessionId: string) => Promise<void>,
-  voiceboxManager?: VoiceboxManager,
+  /** Called when browser sends webrtc-accept (callId + sessionId linking). */
+  onWebRtcAccept?: (callId: string, sessionId: string) => void,
 ): void {
   const WEB_PORT = 3060;
 
@@ -382,6 +384,7 @@ export function initWebUi(
         if (msg.type === 'webrtc-offer' && msg.sessionId) {
           // Forward to Rust proxy-engine for WebRTC handling.
           if (onWebRtcOffer) {
+            log(`[webrtc-ws] offer msg keys: ${Object.keys(msg).join(',')}, sdp type: ${typeof msg.sdp}, sdp len: ${msg.sdp?.length || 0}`);
             onWebRtcOffer(msg.sessionId, msg.sdp, socket as any).catch((e: any) =>
               log(`[webrtc] offer error: ${e.message}`));
           }
@@ -394,8 +397,10 @@ export function initWebUi(
             onWebRtcClose(msg.sessionId).catch(() => {});
           }
         } else if (msg.type === 'webrtc-accept' && msg.callId) {
-          // TODO: Wire to Rust call linking.
           log(`[webrtc] accept: call=${msg.callId} session=${msg.sessionId || 'none'}`);
+          if (onWebRtcAccept && msg.sessionId) {
+            onWebRtcAccept(msg.callId, msg.sessionId);
+          }
         } else if (msg.type?.startsWith('webrtc-')) {
           msg._remoteIp = remoteIp;
           handleWebRtcSignaling(socket as any, msg);