Implements comprehensive user management interface for admin panel:
- Search and filter users by username, class, and active status
- Sort by username, level, balance, or XP with pagination
- View and edit user details (balance, XP, level, class, daily streak, active status)
- Manage user inventories (add/remove items with quantities)
- Debounced search input (300ms delay)
- Responsive design (mobile full-screen, desktop slide-in panel)
- Draft state management with unsaved changes tracking
- Keyboard shortcuts (Escape to close detail panel)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
