Fix: Fonts selbst hosten (next/font/local) + Bootstrap an Superadmin-Store anpassen

- next/font/google lud Open Sans/Poppins zur Build-Zeit von Google -> flakiger
  'Failed to fetch from Google Fonts' bricht den Prod-Build ab. Jetzt committete
  woff2 (src/app/fonts) via next/font/local -> reproduzierbarer Offline-Build, DSGVO.
- scripts/bootstrap-admin.ts: provisionTenant nimmt kein isPlatformAdmin mehr; der
  Superadmin ist jetzt das eigene Modell platformAdmin (Login /platform/login, MFA).
  Bootstrap legt Mandant+Mandanten-Admin UND platformAdmin an (idempotent).
- node:22-Docker-Build lokal verifiziert (kompiliert + TypeCheck + Routen).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/layout.tsx

@@ -1,20 +1,33 @@
 import type { Metadata } from "next";
-import { Open_Sans, Poppins } from "next/font/google";
+import localFont from "next/font/local";
 import { NextIntlClientProvider } from "next-intl";
 import { getLocale } from "next-intl/server";
 import "./globals.css";
 
-// Self-hosted über next/font (kein Google-CDN-Aufruf zur Laufzeit, DSGVO)
-const openSans = Open_Sans({
+// Selbst gehostet über next/font/local (committete woff2 in ./fonts) — kein
+// Google-Fonts-Fetch zur Build- oder Laufzeit. DSGVO-konform und macht den
+// Produktiv-Build reproduzierbar/offline (next/font/google lud die Schriften
+// sonst zur Build-Zeit von Google, was flakig fehlschlagen kann).
+const openSans = localFont({
   variable: "--font-open-sans",
-  subsets: ["latin"],
-  weight: ["300", "400", "600", "700"],
+  display: "swap",
+  src: [
+    { path: "./fonts/open-sans-300.woff2", weight: "300", style: "normal" },
+    { path: "./fonts/open-sans-400.woff2", weight: "400", style: "normal" },
+    { path: "./fonts/open-sans-600.woff2", weight: "600", style: "normal" },
+    { path: "./fonts/open-sans-700.woff2", weight: "700", style: "normal" },
+  ],
 });
 
-const poppins = Poppins({
+const poppins = localFont({
   variable: "--font-poppins",
-  subsets: ["latin"],
-  weight: ["300", "500", "600", "700"],
+  display: "swap",
+  src: [
+    { path: "./fonts/poppins-300.woff2", weight: "300", style: "normal" },
+    { path: "./fonts/poppins-500.woff2", weight: "500", style: "normal" },
+    { path: "./fonts/poppins-600.woff2", weight: "600", style: "normal" },
+    { path: "./fonts/poppins-700.woff2", weight: "700", style: "normal" },
+  ],
 });
 
 export const metadata: Metadata = {