feat(review): apply review-memory suppression to review findings before surfacing (advisory only)

[JSONbored]

Apply slice of #1964: at review-composition time, when review.memory is on, run the deterministic matcher over the AI findings and demote/drop matched advisory findings before they hit the unified comment. Advisory findings ONLY — it must NOT alter any gate blocker or the merge/close disposition (maintainer-only). Fail-safe: any error leaves findings untouched.

Deliverables

• Wire the matcher (review-memory-match.ts) into the advisory finding composition path, gated by the resolved review.memory flag
• Suppress/demote only advisory (nit/non-blocking) findings; never touch critical gate blockers
• Fail-safe: store read error or matcher throw => findings pass through unchanged
• Audit note (public-safe count of suppressed findings) for the audit trail
• Tests: flag-off no-op (byte-identical), flag-on suppress/demote, blocker never suppressed, error fail-safe (branch-counted)

References

• src/review/unified-comment.ts:531
• src/services/ai-review.ts:215
• src/review/feature-activation.ts

Part of #1964.

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size: S · held for later release (gittensor:feature once activated)

[linear-code]

JSO-2282