selftune: fold the REGRESSED-verdict track-record rollup into the self-tune cron tick

[JSONbored]

Context

Parent: #8757; closes an OPEN loop from #8140/#8082. scripts/backtest-track-record.ts computes computeRegressedVerdictTrackRecord against persisted backtest results but has zero non-manual callers — a human must remember to run it. Meanwhile runSelfTune (src/review/selftune-wire.ts:152-190, cron via src/queue/job-dispatch.ts:392) already appends report-only rec lines (buildKnobReliabilityRecs :171 precedent).

Requirements

• On the self-tune tick, aggregate the persisted THRESHOLD_BACKTEST_EVENT_TYPE (+ logic-check results if present) via the existing pure aggregator and append a report-only rec line (total runs, regressed count/rate, per-ruleId breakdown) to the tuning-rec output — same payload-less pattern as buildKnobReliabilityRecs.
• Keep the CLI working unchanged (it stays the ad-hoc/deep-dive tool).
• No autonomy: report-only line, no overridePayload.

Deliverables

• The cron-path aggregation + rec line.
• Tests: empty history, some-regressed history, per-rule breakdown rendering.

Test Coverage Requirements

99%+ patch coverage, branch-counted.

[linear-code]

JSO-6053