feat(admin): Betreiber-Panel (/api/admin) mit is_admin-Flag
- 0003_admin.sql: accounts.is_admin
- auth.js: ensureAdminFlag (Konto = ADMIN_EMAIL wird auto-promoted),
is_admin im JWT, requireAdmin-Middleware (prüft DB autoritativ)
- routes/admin.js: GET /stats (Kunden/Abos/Instanzen/MRR), GET /accounts,
GET /accounts/:id/instances, POST /instances/:id/{suspend,reactivate}
- register/login + /account/me liefern is_admin
- ADMIN_EMAIL in .env.example
E2E: Admin-Promotion, Kunde→403, Stats (2 Kunden/MRR 49), Kundenliste.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
karim
6a2393301d