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>

README.md

@@ -68,6 +68,7 @@ gitea-migration/
 ├── lib/common.sh             # Shared functions + .env validators
 ├── setup/
 │   ├── configure_env.sh      # Interactive .env wizard (~65 prompts)
+│   ├── configure_runners.sh  # Interactive runner definition wizard
 │   ├── macbook.sh            # Local prerequisites (brew packages)
 │   ├── unraid.sh             # Remote prerequisites (static binaries)
 │   ├── fedora.sh             # Remote prerequisites (dnf packages)
@@ -89,7 +90,7 @@ gitea-migration/
 ├── backup/
 │   ├── backup_primary.sh     # Gitea dump, SCP to Fedora
 │   └── restore_to_primary.sh # Restore dump to Unraid
-├── preflight.sh              # 22 pre-flight validation checks
+├── preflight.sh              # 24 pre-flight validation checks
 ├── run_all.sh                # Full pipeline orchestration
 ├── teardown_all.sh           # Reverse teardown (9 to 1)
 ├── manage_runner.sh          # Dynamic runner add/remove/list