feat: update admin panel keyboard structure and registration button logic

- Updated admin panel keyboard to match admin_panel.py handlers
- Changed registration button logic: show only for unregistered non-admins
- Added missing methods to IBotController interface
- Updated get_main_keyboard to accept is_registered parameter
- Simplified admin panel structure with proper callback routing
- Removed test callback button from production UI
- Created ADMIN_PANEL_STRUCTURE.md and ADMIN_PANEL_TESTING.md documentation

main.py

@@ -92,7 +92,7 @@ async def admin_panel_handler(callback: CallbackQuery):
 
 @router.callback_query(F.data == "lottery_management")
 async def lottery_management_handler(callback: CallbackQuery):
-    """Обработчик управления розыгрышами"""
+    """Обработчик управления розыгрышами (старый callback)"""
     async with get_controller() as controller:
         await controller.handle_lottery_management(callback)