Add auto-labeling rule management UI

[IMax153]

Summary

• add the repository-scoped tabular auto-labeling UI with create, edit, toggle, delete, activity, and conflict recovery flows
• add per-rule names and confidence thresholds, versioned management contracts, and 30-day activity statistics
• add no-write AI and ready-for-review rule testing with recent pull request candidates
• share labeling policy code between API previews and event processing, with accessible Foldkit dialogs and menus

Testing

• affected workspace vp check commands pass
• affected workspace test suites pass (116 tests after final remediation)
• apps/web production build passes
• git diff --check origin/main...HEAD passes

Infrastructure

• labeling schema changes are folded into the existing create-table and seed migrations because this environment will be torn down and reapplied rather than upgraded in place