feat(review): read promoted self-tune overrides into the live gate

[JSONbored]

Summary

The self-improvement loop (GITTENSORY_REVIEW_SELFTUNE, default OFF) already shadow-soaks and promotes tightening-only overrides into tunables_overrides — but nothing read them back, so a promoted override sat inert (the read-back was explicitly deferred in selftune-wire.ts pending a gittensory-native tightening tunable).

This wires the live read-back in resolveRepositorySettings:

• applySelfTuneOverrideToSettings (pure) translates a promoted confidenceFloor [0,1] into gittensory's native readiness tunable by raising an existing qualityGateMinScore to round(confidenceFloor * 100) via max().
• Tightening-only by construction: it never creates a readiness gate the operator didn't set (a null threshold stays null), and never lowers an existing one. Since the loop only ever populates the would-merge error side (so the advisor can only raise the floor), the recommendation reaches the live gate with zero risk of loosening it.
• Flag-OFF (default): the override is never read and settings are byte-identical to before.

Closes the last open gap in the converged self-improvement loop.

Scope

• src/settings/repository-settings.ts — the flag-gated read-back + pure translator
• src/review/selftune-wire.ts — comment update (the deferred read-back is now wired)
• test/unit/selftune-readback.test.ts — new

Validation

• npm run test:coverage — 4618 passed; repository-settings.ts at 100% line+branch on the diff
• npm run typecheck — clean
• Tests cover: raise-existing, never-lower (no-op), never-create (null threshold), no-override/no-floor, and flag ON vs OFF end-to-end

Safety

• No secrets / private terms. No public-surface change. Default-OFF flag; tightening-only invariant tested.

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.45%. Comparing base (d984a29) to head (7e31e5a).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1495   +/-   ##
=======================================
  Coverage   95.45%   95.45%           
=======================================
  Files         195      195           
  Lines       21111    21121   +10     
  Branches     7632     7637    +5     
=======================================
+ Hits        20151    20161   +10     
  Misses        383      383           
  Partials      577      577           

Files with missing lines	Coverage Δ
src/review/selftune-wire.ts	92.30% <ø> (ø)
src/settings/repository-settings.ts	100.00% <100.00%> (ø)

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