Preserve persisted thread git info in resume (#13504)

## Summary
- ensure `thread.resume` reuses the stored `gitInfo` instead of
rebuilding it from the live working tree
- persist and apply thread git metadata through the resume flow and add
a regression test covering branch mismatch cases

## Testing
- Not run (not requested)

codex-rs/app-server/src/thread_state.rs

@@ -26,6 +26,7 @@ pub(crate) struct PendingThreadResumeRequest {
     pub(crate) request_id: ConnectionRequestId,
     pub(crate) rollout_path: PathBuf,
     pub(crate) config_snapshot: ThreadConfigSnapshot,
+    pub(crate) thread_summary: codex_app_server_protocol::Thread,
 }
 
 // ThreadListenerCommand is used to perform operations in the context of the thread listener, for serialization purposes.