constitution: make Gatehouse advisory gate enforceable (v1.9.0)

[fatherlinux]

Rationale

§XII already declared Gatehouse an advisory gate ("do not block merge"), but nothing in the doctrine stopped adopters from wiring the review job as a required status check. That happened: on crunchtools/mcp-trentina#56, the review — configured as required — blocked an otherwise-green PR on three separate runs, each producing a different set of all-false HIGH findings (see crunchtools/gatehouse#23). The PR had to be admin-merged.

Change

Strengthens §XII → Gatehouse to make "advisory" enforceable, not just aspirational:

• The review job is advisory by construction — the reusable workflow exits 0 regardless of findings by default.
• It MUST NOT be configured as a required status check.
• Blocking is opt-in (blocking: true input) and, even when enabled, still MUST NOT be a required check.
• Clarifies that the guard job is the one to mark required.

Bumps 1.8.0 → 1.9.0 (new governance constraint) with a ratification-history row.

Companion PR

The gatehouse implementation that makes the reusable workflow honor this: crunchtools/gatehouse#24.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request updates the CrunchTools Constitution to version 1.9.0, specifying that the Gatehouse AI review job is advisory and must not be configured as a required status check. The review feedback suggests minor improvements to formatting consistency, such as enclosing the review job in backticks and refining the phrasing to align with RFC-style standards.

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[gemini-code-assist]

For consistency with other job references (like guard), the review job should be enclosed in backticks. Additionally, adding a comma after 'enabled' improves readability.

Suggested change

- **The review job is advisory by construction and MUST NOT be a required status check.** An LLM reviewer is non-deterministic and hallucinates findings; giving it merge authority forces maintainers to either bypass branch protection or "fix" non-bugs. The reusable workflow exits `0` regardless of findings by default. Blocking behavior is opt-in only (the workflow's `blocking: true` input), and even when enabled the review job MUST NOT be added to branch protection as a required check.

- **The `review` job is advisory by construction and MUST NOT be a required status check.** An LLM reviewer is non-deterministic and hallucinates findings; giving it merge authority forces maintainers to either bypass branch protection or "fix" non-bugs. The reusable workflow exits `0` regardless of findings by default. Blocking behavior is opt-in only (the workflow's `blocking: true` input), and even when enabled, the `review` job MUST NOT be added to branch protection as a required check.

[gemini-code-assist]

The phrase 'It, not the review job, is the one to mark required' is slightly awkward and lacks the RFC-style formatting used elsewhere in the constitution. Enclosing review in backticks also ensures consistency with guard.

Suggested change

	- The `guard` job is a **blocking gate** — PRs from non-members that modify `.github/workflows/` MUST be rejected. It, not the review job, is the one to mark required.
	- The `guard` job is a **blocking gate** — PRs from non-members that modify `.github/workflows/` MUST be rejected. It, not the `review` job, MUST be configured as a required status check.