fix(admin): persist data directory and pass env vars

app/admin/smtp/page.tsx

@@ -0,0 +1,28 @@
+import { redirect } from "next/navigation";
+import AdminShell from "@/components/admin/AdminShell";
+import { requireAdminSession } from "@/lib/admin/auth";
+import { getSmtpSettings } from "@/lib/admin/store";
+
+export default async function AdminSmtpPage() {
+  if (!await requireAdminSession()) redirect("/admin/login");
+  const settings = await getSmtpSettings();
+
+  return (
+    <AdminShell>
+      <div className="admin-page-head">
+        <p className="eyebrow">E-Mail</p>
+        <h1>SMTP Einstellungen</h1>
+      </div>
+      <form className="admin-card admin-form" action="/api/admin/smtp" method="post">
+        <label>SMTP Server<input name="host" defaultValue={settings.host} /></label>
+        <label>Port<input name="port" defaultValue={settings.port} inputMode="numeric" /></label>
+        <label>Benutzername<input name="username" defaultValue={settings.username} /></label>
+        <label>Passwort<input name="password" type="password" placeholder="wird in dieser Foundation noch nicht gespeichert" disabled /></label>
+        <label>Absenderadresse<input name="fromAddress" type="email" defaultValue={settings.fromAddress} /></label>
+        <label>Antwortadresse<input name="replyToAddress" type="email" defaultValue={settings.replyToAddress} /></label>
+        <label className="admin-checkbox"><input name="tls" type="checkbox" defaultChecked={settings.tls} /> TLS aktivieren</label>
+        <button className="button" type="submit">Speichern</button>
+      </form>
+    </AdminShell>
+  );
+}