Completes the OpenSpec lifecycle for the implementation merged in #196:
- openspec archive branch-protection-management -> live spec
openspec/specs/branch-protection/spec.md (7 requirements).
- Change moved to changes/archive/2026-06-02-branch-protection-management/.
- Showboat demo moved next to the live spec
(openspec/specs/branch-protection/branch-protection.demo.md); spec link fixed.
openspec validate --all --strict: 17/17. check-demos: 0 errors.
Closes forgejo-mcp-uc6.