docs: fix stale references across all documentation
README.md: add missing configure_runners.sh, fix check count 22→24
USAGE_GUIDE.md: fix check refs 23-24→21-22, add CAP column to
manage_runner list example
PLAN.md: fix mirror-sync→push_mirrors-sync endpoint
contracts/gitea-api.md: add 5 missing endpoints (DELETE tokens,
repo-scoped runner registration, PUT/POST GitHub Pages, GitHub
commits), remove unused actions/workflows endpoint, fix
GET /settings/api Used-in to include Phase 2
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
045283be50