Stops the legacy run-log dual-write, auto-imports remaining rows and drops
the table at state-DB open (table-presence guard: self-heals downgrade
round-trips), keeps the newest 2000 terminal runs per job in the ledger,
retires cron.runLog config via doctor, and moves live-run cancellation to
src/cron behind the shared task control seam.
Part 2 of 2 for #106041.
Adds a SQLite state query-plan regression test and smoke benchmark, wires the smoke artifact into source performance evidence, validates SQLite smoke output in the performance summary, and removes a retired ClawHub nav entry that broke docs link checks.
Fixes#91616
