ci(gitflow): enforce branch and PR governance checks

docs/product-engineering/git-flow-governance.md

@@ -0,0 +1,66 @@
+# Git Flow Governance
+
+## Scope
+
+Governance rules for branch protections, PR gates, branch naming, and merge discipline.
+
+## Branch Protection
+
+Protected branches:
+
+- `main`
+- `staging`
+
+Apply protections using:
+
+- Gitea UI settings
+- or automation script: `.gitea/scripts/configure-branch-protection.sh`
+
+Minimum policy:
+
+- no direct pushes
+- PR merge required
+- required status checks
+- at least one reviewer approval
+
+## PR Gates
+
+Required checks are implemented in `.gitea/workflows/ci.yml`:
+
+- Governance Checks
+- Lint Typecheck Unit E2E
+
+## Branch Naming and TODO Scope
+
+Allowed branch prefixes:
+
+- `todo/`
+- `refactor/`
+- `code/`
+
+Validation script:
+
+- `.gitea/scripts/check-branch-name.sh`
+
+Rule:
+
+- one primary TODO item per delivery branch
+
+PR TODO reference enforcement:
+
+- template: `.gitea/PULL_REQUEST_TEMPLATE.md`
+- CI check: `.gitea/scripts/check-pr-todo-reference.sh`
+
+## Branch Lifecycle
+
+1. Create short-lived branch from latest integration tip.
+2. Implement one primary scope.
+3. Open PR and pass required checks.
+4. Merge into `dev`.
+5. Promote `dev -> staging -> main`.
+
+## Commit and Tag Policy
+
+- Conventional commits required (`CONTRIBUTING.md`)
+- release tags: `vX.Y.Z`
+- changelog generated from commit history