UpdateObservation set updated_at_epoch, but the observations table has no such column, so every PUT /api/observations/{id} failed with HTTP 500 (no such column: updated_at_epoch). Remove the assignment; nothing reads an edited-at time. An update that changes nothing now returns the observation, as intended. UpdateObservation had no tests: add store and handler tests.
Co-authored-by: Claude Sonnet 5.5 <[email protected]>
