RunClock ticked from tasks.started_at (the task's first-ever start), so after
a review timeout + retry a healthy current run showed cumulative card age
(e.g. working · 2h for a minutes-old run).
_task_dict() now emits current_run_started_at from the run row
tasks.current_run_id points at (batched single query, same as latest
summaries), and RunClock prefers it, falling back to started_at for older
backends. Fixes#99819.
0ebaf162cc