fix(mac): prevent updater hang on manual install

Bump to 1.0.20. Disable autoDownload during manual check and fix
Squirrel.Mac quitAndInstall race on darwin.

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "TTRPGPlayer",
-  "version": "1.0.19",
+  "version": "1.0.20",
   "description": "TTRPG Player — редактор и проигрыватель НРИ",
   "main": "dist/main/index.cjs",
   "scripts": {