[CI] Add preload and splash to minified builds

.github/workflows/release_nightly.yml

@@ -44,11 +44,15 @@ jobs:
         npx esbuild ./src --bundle --platform=node --external:electron --external:original-fs --external:auto-updater --outfile=index.js
         npx uglifyjs --compress --mangle -o index.js -- index.js
         cp src/package.json .
+        cp src/splash/index.html .
+        cp src/splash/preload.js .
         npx minify-json package.json
         rm -rf src
         mkdir src
         cp index.js src
         cp package.json src
+        cp index.html src
+        cp preload.js src
         npx asar pack src testing.asar
 
     - name: GitHub Release