Cross-cutting review polish:
- worker.go: id/type → job_id/job_type; one stray attempts → attempt for
consistency with the other 4 sites in the same file.
- runners/workspace_fetch.go: ws_id → workspace_id (matches the dispatched
notify.Message metadata key).
- runners/worktree_prune.go: id → worktree_id (same reason).
- runners/worktree_prune_test.go: add TestWorktreePrune_NoRowsIsNoOp for
symmetry with the no-op tests in the other 4 runner test files.
- migrations/0005_jobs.down.sql: comment that DROP TABLE jobs cascades to
drop the three idx_jobs_* indexes automatically.
q792602257