feat(miner-governor): self-reputation throttle from own outcome history

[JSONbored]

A miner whose own recent PRs are trending toward closed/rejected outcomes on a given repo should slow down or pause on that repo rather than continuing to fire submissions at the same rate — a self-correcting throttle distinct from the global/per-repo rate limit, driven by the miner's own historical merge/close ratio rather than a fixed cadence. This is bounded to the miner's own local history and degrades/recovers cadence rather than imposing a permanent block. Open, scored contributor work, provided the fail-open-only-on-insufficient-sample-size behavior is thoroughly tested.

Deliverables

• A selfReputationThrottle(recentOwnOutcomes, thresholds) function the Governor chokepoint consults before an open_pr/file_issue action, reading the miner's own local outcome history (not any shared/cross-fleet data — per the architecture skeleton, this stays 100% local)
• A degrading cadence: as the miner's own recent closed/rejected ratio on a repo rises past a configured threshold, allowed submission frequency to that specific repo drops (not a hard permanent ban — a repo with an improving ratio recovers cadence)
• Configurable thresholds sourced from .gittensory-miner.yml, conservative built-in defaults
• Tests: a clean track record allows normal cadence, a degrading ratio measurably throttles cadence, an empty/insufficient history (new miner, new repo) does not falsely throttle (fails open only on genuinely insufficient sample size, documented explicitly), and a recovering ratio restores cadence
• Throttle decisions recorded to the governor ledger with the outcome ratio that triggered them

References

• src/signals/reward-risk.ts (buildContributorRewardRiskStrategy, buildMaintainerNoiseReport) — the existing outcome-history-driven risk/strategy vocabulary this throttle's shape should stay consistent with, adapted to the miner's own local-only history
• The Governor chokepoint (companion maintainer issue) — this check gates submission write paths alongside the self-plagiarism throttle
• The append-only governor ledger (companion foundation issue) — the local source of the miner's own outcome history this throttle reads

[linear-code]

JSO-2443