docs: fix the review findings on the hook-contract retirement

Why: a review of 4de5b6b and 3c5f6a6 found seven places that still
described the retired external hook contract as current, or that could
pass without checking anything.

Implementation Notes:
- gates.md: drop the "one caveat below" pointer; the caveat is gone.
- SIMPLIFICATION-AUDIT.md: the §7 note now says all but one entry is
  closed and lists 36 (4de5b6b) as struck. Finding 2's count chain gets
  a closing note: pre-push is 8 repo-authored hooks (10 reported).
- .pre-commit-config.yaml: the check-vale-style-sync comment points at
  case 32 (one-plugin narrowing guard), not the deleted case 33.
- ADR-0014: the retirement pointer now covers the ADR-0025 amendment
  above it too, naming case 33 and the exported hook IDs. ADR-0022 gets
  a reciprocal amended-by note on its check-release-needed comparison.
  Historical body text is unchanged.
- test-vale-wrap.sh case 32: property 3 fails when a class's corpus
  regex matches no tracked file, instead of passing vacuously after a
  layout move. The corpus regexes are now globals so a new Part D can
  point them at a missing layout and require that failure.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/spec/gates.md

@@ -14,7 +14,7 @@ of the oddities documented here are load-bearing and have already been re-litiga
 | Command | Scope |
 |---|---|
 | `pre-commit run --all-files` | the commit-stage hooks |
-| `pre-commit run --hook-stage pre-push --all-files` | the push gate, one command — with one caveat below |
+| `pre-commit run --hook-stage pre-push --all-files` | the push gate, one command |
 | `pre-commit run skill-size-check --all-files` | just the ADR-0020 size/context gates |
 
 Install hooks via `pc-run`, wiring **all three stages**. This repo's `.pre-commit-config.yaml` has no