Add realtime output modality and transcript events (#17701)

- Add outputModality to thread/realtime/start and wire text/audio output
selection through app-server, core, API, and TUI.\n- Rename the realtime
transcript delta notification and add a separate transcript done
notification that forwards final text from item done without correlating
it with deltas.

codex-rs/tui/src/chatwidget/realtime.rs

@@ -7,6 +7,7 @@ use codex_protocol::protocol::RealtimeConversationClosedEvent;
 use codex_protocol::protocol::RealtimeConversationRealtimeEvent;
 use codex_protocol::protocol::RealtimeConversationStartedEvent;
 use codex_protocol::protocol::RealtimeEvent;
+use codex_protocol::protocol::RealtimeOutputModality;
 use codex_realtime_webrtc::RealtimeWebrtcEvent;
 use codex_realtime_webrtc::RealtimeWebrtcSession;
 use codex_realtime_webrtc::RealtimeWebrtcSessionHandle;
@@ -236,6 +237,7 @@ impl ChatWidget {
     ) {
         self.submit_op(AppCommand::realtime_conversation_start(
             ConversationStartParams {
+                output_modality: RealtimeOutputModality::Audio,
                 prompt: None,
                 session_id: None,
                 transport,
@@ -327,7 +329,9 @@ impl ChatWidget {
             }
             RealtimeEvent::InputAudioSpeechStarted(_) => self.interrupt_realtime_audio_playback(),
             RealtimeEvent::InputTranscriptDelta(_) => {}
+            RealtimeEvent::InputTranscriptDone(_) => {}
             RealtimeEvent::OutputTranscriptDelta(_) => {}
+            RealtimeEvent::OutputTranscriptDone(_) => {}
             RealtimeEvent::AudioOut(frame) => self.enqueue_realtime_audio_out(&frame),
             RealtimeEvent::ResponseCreated(_) => {}
             RealtimeEvent::ResponseCancelled(_) => self.interrupt_realtime_audio_playback(),