"feat: Update database schema for improved performance"

backend/app/app.py

@@ -1463,11 +1463,18 @@ def admin_page():
         
         # Scheduler-Status laden
         if active_tab == 'scheduler':
-            from utils.scheduler import scheduler_is_running
-            scheduler_status = {
-                "running": scheduler_is_running(),
-                "message": "Der Scheduler läuft" if scheduler_is_running() else "Der Scheduler ist gestoppt"
-            }
+            try:
+                from utils.scheduler import scheduler_is_running
+                is_running = scheduler_is_running()
+                scheduler_status = {
+                    "running": is_running,
+                    "message": "Der Scheduler läuft" if is_running else "Der Scheduler ist gestoppt"
+                }
+            except (ImportError, AttributeError):
+                scheduler_status = {
+                    "running": False,
+                    "message": "Scheduler-Status nicht verfügbar"
+                }
         
         # System-Informationen laden
         if active_tab == 'system':
@@ -3824,8 +3831,11 @@ def clear_admin_cache():
                         app_logger.warning(f"Konnte Cache-Element nicht löschen: {item_path} - {str(e)}")
         
         # Modell-Cache leeren
-        from models import clear_cache
-        clear_cache()
+        try:
+            from models import clear_cache
+            clear_cache()
+        except (ImportError, AttributeError):
+            app_logger.warning("clear_cache Funktion nicht verfügbar")
         
         app_logger.info(f"System-Cache geleert: {cleared_items} Elemente entfernt")
         return jsonify({