Fix: Downloads aus /data/downloads servieren + Electron Build fixen

- Downloads-Pfad von relativem App-Pfad auf DATA_DIR/downloads geändert
- Electron package.json: author Feld ergänzt (Squirrel-Requirement)
- forge.config.js: fehlende Icon-Referenzen entfernt

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

electron/package.json

@@ -3,6 +3,7 @@
   "productName": "Gaming Hub",
   "version": "1.5.0",
   "description": "Gaming Hub Desktop App mit Ad-Blocker",
+  "author": "Gaming Hub",
   "main": "main.js",
   "scripts": {
     "start": "electron .",