Add "ultra" reasoning level for Codex GPT-5.6 Sol and Terra, and expose
Max for Luna (Luna falls back Ultra to Max since it is not supported
upstream). Scoped to cx/ routes only; Kiro and generic OpenAI routing
unchanged.
- Add isActive field to API key schema with migration
- Implement PUT /api/keys/[id] endpoint for toggle
- Update validation to reject paused keys (403)
- Add UI toggle controls with confirmation
- Ensure cloud sync preserves pause state