chore(quality-gates): add gate matrix skill

[BenSheridanEdwards]

Why

AgenticProjectTemplate should be a north-star reference for pre-commit, pre-push, and CI gates. The repo already has strong gates, but agents need a reusable gate-building workflow and a single matrix that explains which stage owns each check and why Biome is not being paired with ESLint.

What Changed

• Added .agents/project/QUALITY_GATES.md with the gate matrix for commit message, pre-commit, pre-push, local proof, CI quality, CodeQL, Lighthouse, and StyleProof.
• Added .claude/skills/build-quality-gates to guide agents through evidence-first hook/workflow/tooling changes.
• Linked the matrix and skill from AGENTS.md, CLAUDE.md, .agents/README.md, TECH_STACK.md, and README.md.
• Documented the Biome boundary: Biome owns lint/format/imports, while TypeScript, RTL, axe, Playwright, Lighthouse, CodeQL, Fallow, and StyleProof own the concerns often delegated to ESLint plugins.

Proof

• python3 /Users/agents/.codex/skills/.system/skill-creator/scripts/quick_validate.py .claude/skills/build-quality-gates
• pnpm check
• pnpm verify
• pnpm e2e
• Visual proof attached or linked, or N/A with reason: N/A — docs and skill-only change; no UI/CSS surface changed.
• StyleProof reviewed, or N/A with reason: N/A — StyleProof passed with No visual changes.
• Other proof: pre-commit hook passed typecheck, staged Biome, Fallow, and gitleaks; pre-push hook passed coverage, build, and E2E.

CI Status

• Latest-sha GitHub Actions are green.
• Pending checks are named below.
• Failing checks are named below with the fix plan.

Latest-sha checks are green: CI quality, Fallow, unit/component tests, production build, E2E behaviour map, security audit, CodeQL, Lighthouse, computed-style visual gate, and StyleProof.

Risk And Rollback

Low risk. This adds documentation and a repo-local skill; it does not change runtime code or gate behavior. Rollback is reverting the single commit if the matrix needs to be split or renamed.

Definition Of Done

• Behaviour is covered by the E2E map when user-visible behaviour changed. (N/A — no product behaviour changed.)
• Logic is unit-tested where logic changed. (N/A — no runtime logic changed.)
• Accessibility was considered and verified for interactive/UI changes. (N/A — no UI changed; existing Playwright axe scan passed.)
• The diff follows .agents/project/ARCHITECTURE.md and CONVENTIONS.md.
• Any new architectural decision is recorded as an ADR. (N/A — this documents the existing gate architecture; no new gate tool was added.)
• No gates were bypassed or weakened.

[github-actions]

Fallow audit report

Found 1 finding.

Details

Severity	Rule	Location	Description
minor	fallow/unused-dev-dependency	package.json:44	Package '@lhci/cli' is in devDependencies but never imported

Generated by fallow.

[github-actions]

Fallow audit report

0 inline findings selected for GitHub review.

[github-actions]

🗺️ StyleProof report

✓ No visual changes detected.