feat(desktop): optional wipe-on-close (Settings -> Sicherheit)

apps/desktop/electron/preload.ts

@@ -159,6 +159,24 @@ const api = {
   // Window fullscreen ------------------------------------------------------
   setFullscreen: (enabled: boolean): Promise<void> =>
     ipcRenderer.invoke(CHANNELS.WINDOW_SET_FULLSCREEN, enabled),
+
+  // Wipe-on-close ----------------------------------------------------------
+  // Subscribe to the main-process pre-quit notification. The renderer's
+  // callback does the actual wipe (memoryWipe.ts) and resolves; we ack
+  // unconditionally so main can finish quitting — better to lose the wipe
+  // than to hang the app shutdown if the callback throws.
+  onWipeBeforeQuit: (cb: () => Promise<void>): Unsubscribe => {
+    const handler = async (_evt: Electron.IpcRendererEvent): Promise<void> => {
+      try {
+        await cb();
+      } catch (err) {
+        console.warn('[wipe] renderer cb failed', err);
+      }
+      ipcRenderer.send(CHANNELS.APP_WIPE_BEFORE_QUIT + ':done');
+    };
+    ipcRenderer.on(CHANNELS.APP_WIPE_BEFORE_QUIT, handler);
+    return () => ipcRenderer.removeListener(CHANNELS.APP_WIPE_BEFORE_QUIT, handler);
+  },
 } as const;
 
 export type ElectronAPI = typeof api;