feat(review): add review.effort_score toggle + "review effort: N/5 (~M min)" line in the unified comment

[JSONbored]

Part of #1955. Add a review.effort_score (bool) display toggle to FocusManifestReviewConfig and render a compact "review effort: N/5 (~M min)" line in the unified review comment (src/review/unified-comment.ts:473) from the estimator. Default off ⇒ byte-identical comment. Depends on the estimator module (sibling bounty).

Deliverables

• Add effortScore (bool | null) to FocusManifestReviewConfig (src/signals/focus-manifest.ts:124); parse review.effort_score in parseReviewConfig (src/signals/focus-manifest.ts:653), serialize in reviewConfigToJson (src/signals/focus-manifest.ts:835), add to present (src/signals/focus-manifest.ts:681)
• Render the compact effort line in renderUnifiedReviewComment (src/review/unified-comment.ts:473), gated on the toggle; absent/false ⇒ line omitted (byte-identical)
• Feed the estimator output (from src/review/review-effort.ts) through buildUnifiedReviewInput (src/review/unified-comment.ts:531)
• Unit tests: toggle on ⇒ line present with correct N/5 + minutes; off/absent ⇒ omitted (snapshot byte-identical); 97% branch

References

• src/review/unified-comment.ts:473
• src/review/unified-comment.ts:531
• src/signals/focus-manifest.ts:124
• #1955

Part of #1955.

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size: S · gittensor:feature

[linear-code]

JSO-2186