AGENTS.md § Gates is the one gate list; cli_contract.GATES and docs verify hold it

The gate list contradicted itself across AGENTS.md, instructions/gates.md and the
command records' gate names. The Rebase-Review Gate is now listed, `new project`'s
exit 42 is no longer a pseudo-gate, gates.md and the explanation page link to the one
list instead of counting, and a register plus a docs verify check keep the three in step.

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- docs/explanation/why-gates-are-code.md
- docs/reference/commands/pages.md
- docs/reference/commands/types-instructions-and-docs.md
- docs/reference/exit-codes.md
- instructions/gates.md
- tools/CONTRACT.md
- tools/chemenu/cli_contract.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/git_publish.py
- tools/chemenu/commands/new_page.py
- tools/chemenu/errors.py
- tools/chemenu/mcp/server.py
- tools/chemenu/tests/test_cli_contract.py
- tools/chemenu/tests/test_docs_verify.py
- tools/chemenu/tests/test_git_publish.py
- tools/chemenu/tests/test_reference_doc.py

Co-Authored-By: Claude Code <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

CHANGES.md

@@ -14,7 +14,7 @@ place only: `instructions/dev/version-parts.md` § The candidate model.
 
 ---
 
-## 9.0.0-beta.8 - 2026-10-07 - Die Formen der vier handgeschriebenen .wikitool-*.json stehen je in einem Datensatz (config_shapes), aus dem Lader, doctor und die Konfigurationsreferenz lesen
+## 9.0.0-beta.9 - 2026-10-07 - Gate-Liste: AGENTS.md § Gates ist die eine Liste (mit Rebase-Review Gate), cli_contract.GATES hält sie, docs verify vergleicht beide
 
 **Author:** Torben Nehmer
 
@@ -33,6 +33,7 @@ place only: `instructions/dev/version-parts.md` § The candidate model.
 - docs/: how-to guides, configuration reference and two explanation pages carved out of README.md, INSTALL.md, INSTALL-MCP.md and EVALS.md; the last two retired
 - INSTALL.md is an English installation tutorial; new tutorial from a first source to a first answer with a shipped sample; README.md a landing page
 - Die Formen der vier handgeschriebenen .wikitool-*.json stehen je in einem Datensatz (config_shapes), aus dem Lader, doctor und die Konfigurationsreferenz lesen
+- Gate-Liste: AGENTS.md § Gates ist die eine Liste (mit Rebase-Review Gate), cli_contract.GATES hält sie, docs verify vergleicht beide
 
 **Low impact**
 - version bump: Abschlussmeldung nennt Stichpunkt oder Themenabsatz statt pauschal Prosa