feat(config): add review.max_findings caps for blockers/nits

[JSONbored]

Add review.max_findings ({ blockers?, nits? } ints) capping how many blockers/nits render in the unified comment, so verbose model output stays digestible. Deterministic truncation with a '+N more' note; unset ⇒ no cap (byte-identical). Display-only; net-new vs #1959's listed knobs.

Deliverables

• Add a maxFindings: { blockers: number | null; nits: number | null } sub-object to FocusManifestReviewConfig in src/signals/focus-manifest.ts, parsed as non-negative ints (warn+ignore invalid)
• Wire parse + reviewConfigToJson + present + EMPTY literals
• Truncate the rendered blockers/nits lists in src/review/unified-comment.ts with a deterministic '+N more' footer; never drop a blocker from the GATE decision, only from display
• Unit tests: cap applied, under-cap unchanged, unset=no cap byte-identical, invalid warns; branch coverage on truncate/no-truncate arms and the gate-invariant
• Document review.max_findings in .gittensory.yml.example

References

• src/review/unified-comment.ts:64 (blockers/nits arrays)
• src/signals/focus-manifest.ts:426 (numeric parse pattern)
• .gittensory.yml.example
• part of #1959 (epic #1953)

Part of #1959.

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size: S · gittensor:feature

[linear-code]

JSO-2166