feat(backend): Statistik- und Reporting-Endpunkte (Modul 27)

Aggregations-Endpunkte fuer Voelker, Koeniginnen, Bienenstaende, Varroa,
Honig und Fuetterung nach Lastenheft Abschnitt 4.26.

ApiCore-Backend/src/app.module.ts

@@ -27,6 +27,7 @@ import { BottlingModule } from './bottling/bottling.module';
 import { EquipmentModule } from './equipment/equipment.module';
 import { CalendarModule } from './calendar/calendar.module';
 import { NotificationsModule } from './notifications/notifications.module';
+import { StatisticsModule } from './statistics/statistics.module';
 import { JwtAuthGuard } from './auth/guards/jwt-auth.guard';
 import { RolesGuard } from './auth/guards/roles.guard';
 
@@ -59,6 +60,7 @@ import { RolesGuard } from './auth/guards/roles.guard';
     EquipmentModule,
     CalendarModule,
     NotificationsModule,
+    StatisticsModule,
   ],
   controllers: [],
   providers: [