feat(backend): Benachrichtigungssystem (Modul 26)

NotificationsModule: Notification-Modell mit Prioritaeten INFO/
HINWEIS/WARNUNG/KRITISCH, GET /notifications (eigene + Broadcast),
POST /notifications/:id/read. record() als interne API fuer
kuenftige Automatisierungsregeln (Modul 30) vorgesehen.

ApiCore-Backend/src/notifications/notifications.service.spec.ts

@@ -0,0 +1,74 @@
+import { NotFoundException } from '@nestjs/common';
+import { NotificationsService } from './notifications.service';
+import { PrismaService } from '../prisma/prisma.service';
+
+describe('NotificationsService', () => {
+  let service: NotificationsService;
+  let prisma: {
+    notification: {
+      create: jest.Mock;
+      findMany: jest.Mock;
+      findUnique: jest.Mock;
+      update: jest.Mock;
+    };
+  };
+
+  beforeEach(() => {
+    prisma = {
+      notification: {
+        create: jest.fn(),
+        findMany: jest.fn(),
+        findUnique: jest.fn(),
+        update: jest.fn(),
+      },
+    };
+    service = new NotificationsService(prisma as unknown as PrismaService);
+  });
+
+  it('records a notification with the given priority and message', async () => {
+    const created = {
+      id: 'n1',
+      priority: 'KRITISCH',
+      message: 'Keine Königin gesehen',
+    };
+    prisma.notification.create.mockResolvedValueOnce(created);
+
+    const result = await service.record({
+      priority: 'KRITISCH',
+      message: 'Keine Königin gesehen',
+    });
+
+    expect(result).toEqual(created);
+    expect(prisma.notification.create).toHaveBeenCalledWith({
+      data: { priority: 'KRITISCH', message: 'Keine Königin gesehen' },
+    });
+  });
+
+  it('lists notifications for a user including broadcast notifications', async () => {
+    await service.findAll({ userId: 'user-1' });
+
+    const [[queryArg]] = prisma.notification.findMany.mock.calls as [
+      [{ where: { OR?: { userId: string | null }[] } }],
+    ];
+    expect(queryArg.where.OR).toEqual([{ userId: 'user-1' }, { userId: null }]);
+  });
+
+  it('throws NotFoundException when marking an unknown notification as read', async () => {
+    prisma.notification.findUnique.mockResolvedValueOnce(null);
+    await expect(service.markRead('missing')).rejects.toBeInstanceOf(
+      NotFoundException,
+    );
+  });
+
+  it('marks a notification as read', async () => {
+    prisma.notification.findUnique.mockResolvedValueOnce({
+      id: 'n1',
+      read: false,
+    });
+    prisma.notification.update.mockResolvedValueOnce({ id: 'n1', read: true });
+
+    const result = await service.markRead('n1');
+
+    expect(result.read).toBe(true);
+  });
+});