docs: reconcile harness review with landed implementation

[LeXwDeX]

Summary

Post-merge review found three drift points between docs/harness-review-2026-08-16.md and what actually shipped; this aligns the document without changing any decision:

1. A-1: the review gate stayed in dag.complete with a skipReviewGate option for the natural loop path (not relocated to the tool layer) — semantically equivalent and additionally covers the HTTP explicit-complete surface.
2. A4.1: the verify fingerprint binding applies to aggregated routes only; canonical chains intentionally keep no binding to preserve the stronger chain byte-identity acceptance criterion (document conflict resolved in favor of byte-identity).
3. A4.2: marked fixed by fix(dag): complete workflows at rejected review checkpoints instead of failing them #300 (checkpoint completion + unresolved_reviews status field).

Adds appendix B, a decision-to-PR reconciliation table (PR #298/#299/#300/#301 + config PR #9).

Docs only; no code paths touched.