feat(mixer): enhance mixer functionality with interaction and tool legs

- Updated mixer to handle participant and isolated leg roles, allowing for IVR and consent interactions.
- Introduced commands for starting and canceling interactions, managing tool legs for recording and transcription.
- Implemented per-source audio handling for tool legs, enabling separate audio processing.
- Enhanced DTMF handling to forward events between participant legs only.
- Added support for PCM recording directly from tool legs, with WAV file generation.
- Updated TypeScript definitions and functions to support new interaction and tool leg features.

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

@@ -50,11 +50,13 @@ pub fn spawn_sip_inbound(
                         continue; // Too small for RTP header.
                     }
                     let pt = buf[1] & 0x7F;
+                    let marker = (buf[1] & 0x80) != 0;
+                    let timestamp = u32::from_be_bytes([buf[4], buf[5], buf[6], buf[7]]);
                     let payload = buf[12..n].to_vec();
                     if payload.is_empty() {
                         continue;
                     }
-                    if inbound_tx.send(RtpPacket { payload, payload_type: pt }).await.is_err() {
+                    if inbound_tx.send(RtpPacket { payload, payload_type: pt, marker, timestamp }).await.is_err() {
                         break; // Channel closed — leg removed.
                     }
                 }