Add realtime voice selection (#17176)

- Add realtime voice selection for realtime/start.
- Expose the supported v1/v2 voice lists and cover explicit, configured,
default, and invalid voice paths.

codex-rs/rollout/src/policy.rs

@@ -160,6 +160,7 @@ fn event_msg_persistence_mode(ev: &EventMsg) -> Option<EventPersistenceMode> {
         | EventMsg::GetHistoryEntryResponse(_)
         | EventMsg::UndoStarted(_)
         | EventMsg::McpListToolsResponse(_)
+        | EventMsg::RealtimeConversationListVoicesResponse(_)
         | EventMsg::McpStartupUpdate(_)
         | EventMsg::McpStartupComplete(_)
         | EventMsg::ListSkillsResponse(_)