Preserve namespaces on custom tool calls (#30302)

## Summary

- Preserve the optional namespace on custom tool calls during response
deserialization and app-server replay.
- Use the namespaced tool identifier for streaming argument handling and
tool dispatch.
- Regenerate app-server protocol schemas.
- Add regression tests covering namespace serialization and routing.

## Testing

- Ran affected protocol and app-server test suites.
- Ran the full core test suite; two load-sensitive timing tests passed
when rerun individually.
- Ran Clippy and formatting checks.
- Verified with a local end-to-end app-server replay that the namespace
is preserved through the complete request/response flow.

codex-rs/core/src/codex_delegate_tests.rs

@@ -80,6 +80,7 @@ async fn forward_events_cancelled_while_send_blocked_shuts_down_delegate() {
                     status: None,
                     call_id: "call-1".to_string(),
                     name: "tool".to_string(),
+                    namespace: None,
                     input: "{}".to_string(),
                     internal_chat_message_metadata_passthrough: None,
                 },