feat(users): Willkommensmail mit Wellen-Kopf und Logo, Spalte Letzte Anmeldung

POST /users/:id/welcome-mail (gleiche Rechte wie Bearbeiten, jederzeit sendbar),
GET /users/welcome-mail/status; HTML-Mail (Tabellenlayout, Inline-Stile,
Kopfbild als CID-PNG aus assets/mail/welcome-header.svg, erzeugt mit
scripts/render-mail-header.mjs) plus Textfassung. Verzeichniskonten: Hinweis
auf Windows-Passwort; lokale Konten: Link Passwort festlegen (7 Tage, einmalig).
Neue Spalte User.welcomeMailSentAt (Migration 20260930120000). Benutzerliste:
Spalte Letzte Anmeldung, Zeilenaktionen als Symbole. Dockerfile kopiert
apps/api/assets. Lokal per MailHog nachgewiesen.

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

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

@@ -1,6 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import * as nodemailer from 'nodemailer';
-import { MailService } from './mail.service';
+import { MailService, WELCOME_HEADER_CID } from './mail.service';
 
 /**
  * MailService.spec — NEU (260914-eym, Etappe 3c, WINDOWS #30). Der Bereich
@@ -166,7 +166,11 @@ describe('MailService — Transport je Versand nach Mandant des Empfaengers (260
     const service = new MailService(settings as any, makeFakeConfig({}) as any);
 
     await service.sendPasswordResetEmail('alice@a.example.invalid', 'tok-a', 't1');
-    await service.sendWelcomeEmail('bob@b.example.invalid', 'bob', 't2');
+    await service.sendWelcomeMail('t2', 'bob@b.example.invalid', {
+      subject: 'Willkommen bei Tessera',
+      text: 'Guten Tag bob,',
+      html: '<p>bob</p>',
+    });
 
     expect(settings.getDecryptedSmtpConfig.mock.calls.map((c) => c[0])).toEqual(['t1', 't2']);
     const transports = vi.mocked(nodemailer.createTransport).mock.calls.map((c) => c[0] as any);
@@ -314,3 +318,47 @@ describe('MailService.sendReminderEmail (quick-260929-if2, E-04/E-07, T-IF2-05)'
     expect(mockClose).toHaveBeenCalledTimes(1);
   });
 });
+
+describe('MailService.sendWelcomeMail / hasConfiguredTransport (Willkommensmail)', () => {
+  it('haengt das Kopfbild als CID-Anhang an, reicht HTML und Text durch und wirft Transportfehler nach aussen', async () => {
+    const service = new MailService(makeFakeSettings({ t1: configA }) as any, makeFakeConfig({}) as any);
+
+    await service.sendWelcomeMail('t1', 'neu@a.example.invalid', {
+      subject: 'Willkommen bei Tessera',
+      text: 'Text',
+      html: `<img src="cid:${WELCOME_HEADER_CID}">`,
+    });
+
+    const sent = mockSendMail.mock.calls[0][0] as any;
+    expect(sent.from).toBe('noreply@a.example.invalid');
+    expect(sent.html).toContain(`cid:${WELCOME_HEADER_CID}`);
+    expect(sent.text).toBe('Text');
+    expect(sent.attachments).toHaveLength(1);
+    expect(sent.attachments[0].cid).toBe(WELCOME_HEADER_CID);
+    expect(sent.attachments[0].contentType).toBe('image/png');
+    // PNG-Signatur: das Bild aus apps/api/assets/mail ist wirklich geladen.
+    expect((sent.attachments[0].content as Buffer).subarray(1, 4).toString()).toBe('PNG');
+
+    mockSendMail = vi.fn(async () => {
+      throw new Error('ECONNREFUSED');
+    });
+    await expect(
+      service.sendWelcomeMail('t1', 'neu@a.example.invalid', { subject: 'S', text: 'T', html: 'H' }),
+    ).rejects.toThrow('ECONNREFUSED');
+  });
+
+  it('hasConfiguredTransport: SmtpConfig des Mandanten oder MAIL_HOST/TESSERA_SMTP_HOST — der Rueckfall localhost:1025 zaehlt nicht', async () => {
+    expect(
+      await new MailService(makeFakeSettings({ t1: configA }) as any, makeFakeConfig({}) as any).hasConfiguredTransport('t1'),
+    ).toBe(true);
+    expect(
+      await new MailService(makeFakeSettings({}) as any, makeFakeConfig({ MAIL_HOST: 'smtp.example.invalid' }) as any).hasConfiguredTransport('t1'),
+    ).toBe(true);
+    expect(
+      await new MailService(makeFakeSettings({}) as any, makeFakeConfig({ TESSERA_SMTP_HOST: 'legacy.example.invalid' }) as any).hasConfiguredTransport('t1'),
+    ).toBe(true);
+    expect(
+      await new MailService(makeFakeSettings({}) as any, makeFakeConfig({}) as any).hasConfiguredTransport('t1'),
+    ).toBe(false);
+  });
+});