feat: Add electron-packager and GitHub Actions for desktop builds

- Add electron-packager as alternative build tool
- Create GitHub Actions workflow for automated Windows builds
- Update .gitignore to exclude dist folder
- Add comprehensive README with installation and usage instructions
- Successfully built Windows executable (210MB)

package.json

@@ -35,7 +35,8 @@
   },
   "devDependencies": {
     "electron": "^39.2.7",
-    "electron-builder": "^26.0.12"
+    "electron-builder": "^26.0.12",
+    "electron-packager": "^17.1.2"
   },
   "build": {
     "appId": "com.beyondcloud.smtptester",
@@ -80,4 +81,4 @@
       "artifactName": "${productName}-${version}-portable.${ext}"
     }
   }
-}
+}