Fail the batch job when recording its end fails, and reconcile orphans

finishBatch now returns its error, and treats a batch that is no longer
running as one, so a batch job never ends succeeded with its batch still
running. A batch left pending or running with its job ended (process
stopped, or the final status write failed) is failed inside startBatch,
before the active batch is read, so it never blocks a manual or
replenish batch. This replaces the boot-only FailInterruptedBatches.

Document suggestions.name in the architecture schema summary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

migrations/queries/suggestions.sql

@@ -35,9 +35,8 @@ WHERE id = ? AND status IN ('pending', 'running');
 
 -- name: FailOrphanedSuggestionBatches :execrows
 -- Fails every batch still pending or running whose job is no longer queued
--- or running: the process stopped before its handler recorded a result.
--- Run at boot, after the job runner fails the jobs a previous process left
--- running.
+-- or running: the process stopped, or recording the batch's end failed,
+-- before its handler recorded a result. Run before reading the active batch.
 UPDATE suggestion_batches
 SET status = 'failed', updated_at = sqlc.arg(updated_at)
 WHERE status IN ('pending', 'running')