fix: Superadmin wird direkt zu /admin weitergeleitet

- Login: superadmin → /admin, alle anderen → /search
- Cached-Session: superadmin → /admin
- Search-Seite: superadmin wird sofort zu /admin umgeleitet

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/page.tsx

@@ -18,8 +18,9 @@ export default function LoginPage() {
 
   useEffect(() => {
     // Only redirect if we have a cached session — no API call, no loop risk
-    if (getCachedUser() !== null) {
-      router.replace("/search");
+    const cached = getCachedUser();
+    if (cached !== null) {
+      router.replace(cached.role === "superadmin" ? "/admin" : "/search");
     }
   }, [router]);
 
@@ -29,8 +30,9 @@ export default function LoginPage() {
     setLoading(true);
 
     try {
-      await login(username, password);
-      router.push("/search");
+      const res = await login(username, password);
+      const role = res?.user?.role ?? "";
+      router.push(role === "superadmin" ? "/admin" : "/search");
     } catch {
       setError("Anmeldung fehlgeschlagen. Bitte Zugangsdaten pruefen.");
     } finally {

src/app/search/page.tsx

@@ -114,9 +114,16 @@ export default function SearchPage() {
     [query, fromFilter, toFilter, dateFrom, dateTo, sort, hasAttachment, selectedLabelId]
   );
 
+  // Superadmin has no mail access — redirect to admin dashboard
+  useEffect(() => {
+    if (user?.role === "superadmin") {
+      router.replace("/admin");
+    }
+  }, [user, router]);
+
   // Alle Mails beim Öffnen der Seite laden — direkt, ohne useCallback-Closure
   useEffect(() => {
-    if (!user) return;
+    if (!user || user.role === "superadmin") return;
     setSearching(true);
     searchEmails({ page: 1, page_size: PAGE_SIZE })
       .then((res) => {