fix: add ESM-compatible __dirname for Electron main process

Author: Michael Cyroll

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nextcloud-deck-electron",
-  "version": "0.9.3",
+  "version": "0.9.4",
   "description": "Standalone macOS app for Nextcloud Deck",
   "type": "module",
   "main": "dist/main/main.js",

src/main/main.ts

@@ -1,5 +1,9 @@
 import { app, BrowserWindow, ipcMain, Menu, type MenuItemConstructorOptions } from 'electron';
 import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
 
 // Electron Store (ESM-kompatibel über dynamischen Import)
 type Preferences = {