Security improvements:
- Removed registration link from login page
- Disabled /auth/register route - redirects with error message
- Removed demo credentials from login page
- Added info message: 'New users are created by administrators'
UI improvements:
- Compacted all admin interface buttons (btn-sm)
- Reduced heading sizes (H2 → H4) for less visual dominance
- Shortened badge texts ('Administrator' → 'Admin', 'Benutzer' → 'User')
- Optimized spacing and reduced margins/paddings
- Cleaner, more professional admin interface
Access control:
- Only administrators can create new users via admin panel
- Self-registration completely disabled for security
- Maintains full admin functionality with improved UX
Features added:
- Admin authentication system with is_admin field
- Complete admin dashboard with user statistics
- User management (create, edit, delete, toggle admin)
- Protected admin routes with @admin_required decorator
- Security features (prevent self-deletion, last admin protection)
- Responsive admin UI with Bootstrap integration
- Database migration script for admin field
- Admin navigation link for authorized users
Technical improvements:
- Enhanced 3-column dashboard layout (tables | editor | saved queries)
- Removed plus button and made right sidebar more compact
- Admin user (admin/admin123) automatically created with admin privileges
- Full CRUD operations for user management
- Flash messages for user feedback
- Form validation and error handling
