PUT /v1/organizations/{id} returns 502 — SQLAlchemy MissingGreenlet on updated_at

## Bug Updating an organization via `PUT /v1/organizations/{id}` returns HTTP 502. ## Root cause The backend FastAPI response serializer tries to lazy-load the `updated_at` field outside an async context, triggering a SQLAlchemy `MissingGreenlet` error: ``` sqlalchemy.exc.MissingGreenlet: greenlet_spawn has not been called; cant call await_only() here. Was IO attempted in an unexpected place? ``` ## Steps to reproduce 1. Create an organization 2. Go to Organization Settings 3. Change the description (or any field) 4. Click Save Changes 5. The save fails — backend returns 502 ## Expected Organization updates should save successfully. ## Impact Organization settings cannot be updated at all. This blocks the org-crud E2E test suite (tests 5-10 fail because test 5 tries to update and gets 502).