Fix desktop Codex chat resume compatibility - #52

Summary

• align bridge Codex app-server requests with desktop Conductor, including initialize/initialized and resume/start payloads
• persist desktop-compatible session metadata for newly created chats so derived chats do not inherit null thinking/personality fields
• add regression coverage for request payloads, session persistence, and new-chat creation

Testing

• npm run typecheck
• npm run lint
• npm test