Task 36c40130-a69a-46ed-a047-2cdc5ee2d2e0, remediation of review findings F23-1 and F23-2 (PR #205). F23-1: StartPhotoBackfill now checks, in the same write transaction that enqueues, for a full backfill_dinner_photos job already queued or running (new GetActivePhotoBackfillJob query) and returns its id instead of enqueuing another, as plan.StartDraft does with GetActiveDraftJob. The claim is the stored job row, so it holds across restarts; a job left running by a stopped process is failed at boot and no longer blocks. F23-2: a dinner whose outcome write fails is still reported failed with grounding_error and the remaining dinners still run, but the job then fails (internal_error, as a ground_dinner job's failed write does) with the per-dinner outcomes published as its result, so it never reports success for state it did not store. Tests: overlapping triggers while queued, after a restart and while running return the one job; a refused dinner write fails the job. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>