feat(260929-if2): Erinnerung zusaetzlich per E-Mail, Doku und Aenderungsliste

- E-Mail-Planer: Anspruch vor dem Senden (genau eine Mail je Faelligkeit, hoechstens 3 Versuche), Systemlesen nur fuer die Kandidatenabfrage
- MailService.sendReminderEmail (Berliner Zeit, nur Text), GET /reminders/email-status, Haken im Formular mit Erklaerung
- Zugriffsklassifikation und Erlaubnisliste fuer forSystem nachgezogen, Aenderungsliste und Anwenderanleitung

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/api/src/reminders/reminders.service.spec.ts

@@ -46,12 +46,18 @@ function makeFakePrisma() {
       ).length;
     }),
   };
-  return { reminder, rows };
+  const user = {
+    findFirst: vi.fn(async ({ where }: { where: any }) => ({
+      email: where.id === 'u-ohne-mail' ? null : `${where.id}@example.invalid`,
+    })),
+  };
+  return { reminder, user, rows };
 }
 
-function setup() {
+function setup(smtp: unknown = { host: 'smtp.example.invalid' }) {
   const prisma = makeFakePrisma();
-  return { prisma, service: new RemindersService(prisma as any) };
+  const settings = { getSmtpConfig: vi.fn(async (_tenantId: string) => smtp) };
+  return { prisma, settings, service: new RemindersService(prisma as any, settings as any) };
 }
 
 const inHours = (h: number) => new Date(Date.now() + h * 3600_000).toISOString();
@@ -244,3 +250,67 @@ describe('RemindersService — loeschen (E-02)', () => {
     expect(prisma.rows.size).toBe(0);
   });
 });
+
+describe('RemindersService — E-Mail-Erinnerung (Aufgabe 3, E-09)', () => {
+  it('getEmailAvailability: SMTP eingerichtet und Adresse vorhanden', async () => {
+    const { service, settings } = setup();
+    await expect(service.getEmailAvailability('t1', 'u1')).resolves.toEqual({
+      smtpConfigured: true,
+      hasEmail: true,
+    });
+    expect(settings.getSmtpConfig).toHaveBeenCalledWith('t1');
+  });
+
+  it('getEmailAvailability: ohne SmtpConfig-Zeile ist der Versand nicht eingerichtet', async () => {
+    const { service } = setup(null);
+    await expect(service.getEmailAvailability('t1', 'u1')).resolves.toEqual({
+      smtpConfigured: false,
+      hasEmail: true,
+    });
+  });
+
+  it('getEmailAvailability: ohne Adresse im Konto hasEmail false, gelesen ueber den gebundenen Klienten', async () => {
+    const { prisma, service } = setup();
+    await expect(service.getEmailAvailability('t1', 'u-ohne-mail')).resolves.toEqual({
+      smtpConfigured: true,
+      hasEmail: false,
+    });
+    expect(forTenant).toHaveBeenLastCalledWith(expect.anything(), 't1', 'u-ohne-mail');
+    expect(prisma.user.findFirst.mock.calls[0]?.[0]?.where).toEqual({ id: 'u-ohne-mail', tenantId: 't1' });
+  });
+
+  it('anlegen mit emailEnabled speichert das Feld, wenn E-Mail moeglich ist', async () => {
+    const { prisma, service } = setup();
+    await service.create('t1', 'u1', { title: 'a', dueAt: inHours(1), emailEnabled: true });
+    expect(prisma.reminder.create.mock.calls[0]?.[0]?.data.emailEnabled).toBe(true);
+  });
+
+  it('anlegen ohne emailEnabled speichert false', async () => {
+    const { prisma, service } = setup();
+    await service.create('t1', 'u1', { title: 'a', dueAt: inHours(1) });
+    expect(prisma.reminder.create.mock.calls[0]?.[0]?.data.emailEnabled).toBe(false);
+  });
+
+  it('anlegen mit emailEnabled ergibt 400, wenn SMTP fehlt oder die Adresse fehlt', async () => {
+    const noSmtp = setup(null);
+    await expect(
+      noSmtp.service.create('t1', 'u1', { title: 'a', dueAt: inHours(1), emailEnabled: true }),
+    ).rejects.toBeInstanceOf(BadRequestException);
+    const noMail = setup();
+    await expect(
+      noMail.service.create('t1', 'u-ohne-mail', { title: 'a', dueAt: inHours(1), emailEnabled: true }),
+    ).rejects.toBeInstanceOf(BadRequestException);
+    expect(noSmtp.prisma.rows.size).toBe(0);
+    expect(noMail.prisma.rows.size).toBe(0);
+  });
+
+  it('aendern mit emailEnabled true ergibt 400 ohne SMTP; emailEnabled false geht immer', async () => {
+    const { prisma, service } = setup(null);
+    seed(prisma, 'x', future());
+    await expect(service.update('t1', 'u1', 'x', { emailEnabled: true })).rejects.toBeInstanceOf(
+      BadRequestException,
+    );
+    await service.update('t1', 'u1', 'x', { emailEnabled: false });
+    expect(prisma.reminder.update.mock.calls[0]?.[0]?.data).toEqual({ emailEnabled: false });
+  });
+});