fix(proxy-engine,codec-lib,sip-proto,ts): preserve negotiated media details and improve RTP audio handling across call legs

rust/crates/proxy-engine/src/main.rs

@@ -677,6 +677,10 @@ async fn handle_webrtc_link(
             "leg_id": session_id,
             "kind": "webrtc",
             "state": "connected",
+            "codec": "Opus",
+            "rtpPort": 0,
+            "remoteMedia": null,
+            "metadata": {},
         }));
 
         respond_ok(out_tx, &cmd.id, serde_json::json!({
@@ -1125,8 +1129,11 @@ async fn handle_add_tool_leg(
             "call_id": call_id,
             "leg_id": tool_leg_id,
             "kind": "tool",
-            "tool_type": tool_type_str,
             "state": "connected",
+            "codec": null,
+            "rtpPort": 0,
+            "remoteMedia": null,
+            "metadata": { "tool_type": tool_type_str },
         }),
     );