fix(activity): an ad-hoc run's row is one run's, a rollback keeps a run whole, Back reads one entry's filters

- The channel-backfill row says "running" from the runs this process has open, not from the table:
  a row whose outcome failed to write no longer reads as running until a restart. The run still
  going leads the row, so a newer run's outcome never sits under the older one's channel.
- Migration 0109's downgrade carries every run's trigger, spend and start in the audit row, and the
  upgrade restores them: a manual run whose admin was deleted stays manual.
- Back/Forward is read by the page's one popstate listener, both halves in one render; the server
  log adopts its half during that render, so no read goes out with one entry's filters and the
  other's range.
- The server log's failed facets use the other tabs' words (the menus may be short); the accounts
  message shows only when the menu really lacks them.

backend/app/jobruns.py

@@ -119,16 +119,6 @@ def recent_runs(db: Session, jobs: list[str], per_job: int) -> dict[str, list[Jo
     return out
 
 
-def running_one(db: Session, job: str) -> JobRun | None:
-    """The newest run of `job` still going, however many runs ended after it started."""
-    return db.scalars(
-        select(JobRun)
-        .where(JobRun.job == job, JobRun.status == RunStatus.RUNNING)
-        .order_by(JobRun.started_at.desc(), JobRun.id.desc())
-        .limit(1)
-    ).first()
-
-
 def gc(db: Session, retention_days: int) -> int:
     """Delete finished runs older than `retention_days` (0 = keep forever). A run still going is
     never reaped. The caller commits."""