- Dashboard: add stats API with content status distribution, recent notifications,
and recent content updates; display active users, pending reviews, unread counts
- User management: full CRUD with role assignment, search, pagination, delete dialog
- Notification center: list with unread filter, mark as read, mark all as read,
pagination, and auto-refresh unread count
- Content editor: form validation (required fields, slug format, blur-triggered
errors), auto-save with 3s debounce and status indicator, publish confirmation
dialog, unsaved changes warning on leave
- Admin layout: add navigation links for user management, roles, and notifications
- admin-api: make request() method public for custom API calls
- gitignore: add reports/mutation/ to exclude mutation test output