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/mcp-server/src/codex_tool_runner.rs

@@ -337,6 +337,7 @@ async fn run_codex_tool_session_inner(
                     | EventMsg::McpToolCallEnd(_)
                     | EventMsg::McpListToolsResponse(_)
                     | EventMsg::ListSkillsResponse(_)
+                    | EventMsg::RealtimeConversationListVoicesResponse(_)
                     | EventMsg::ExecCommandBegin(_)
                     | EventMsg::TerminalInteraction(_)
                     | EventMsg::ExecCommandOutputDelta(_)