L6 Benachrichtigungen & Audit: Glocke, Posteingang, Nutzer-Einstellungen, Mailkonfiguration

- Glocke im Backoffice-Header (ungelesen-Zähler, letzte 10, alle gelesen), mobil
  einbindbar über variant="mobile".
- /notifications mit Filter gelesen/ungelesen/Art, Öffnen markiert gelesen (nur
  relative Links), Pagination.
- /account Abschnitt Benachrichtigungen: E-Mail-Opt-out je Typ, Notdienst Pflicht.
- /settings/email (tenant:manage): Absendername, Antwortadresse, Empfänger Notdienst
  und Abrechnung; Validierung gegen Header-Injection, max. 20 Adressen, Audit.
- Actions unter actions/notifications mit moduleGuard + guard; Navigation ergänzt.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/server/actions/notifications/preferences.ts

@@ -0,0 +1,23 @@
+"use server";
+
+import { revalidatePath } from "next/cache";
+import { moduleGuard } from "@/server/action-guard";
+import { ctxFromGuard } from "@/server/services/context";
+import { setPreferences } from "@/server/services/notifications/preferences";
+
+const guard = moduleGuard("notifications");
+
+export type PreferencesState = { status: "idle" | "saved" | "error" };
+
+/** Save the current user's e-mail opt-outs (checked boxes = e-mail on). */
+export async function saveNotificationPreferences(_prev: PreferencesState, formData: FormData): Promise<PreferencesState> {
+  const g = await guard("notification:read");
+  try {
+    await setPreferences(ctxFromGuard(g), { emailOn: formData.getAll("emailOn").map(String) });
+  } catch (err) {
+    console.error("[notifications] saving preferences failed:", (err as Error).message);
+    return { status: "error" };
+  }
+  revalidatePath("/account");
+  return { status: "saved" };
+}