**Add Vitest support and migrate frontend tests**

- Added Vitest configuration (`vitest.config.mjs`) for frontend unit testing with a `jsdom` environment.
- Migrated and rewrote key frontend tests (`api.test.js`, `comiclist.test.js`, `comicreader.test.js`, `historytable.test.js`, `router.test.js`, `store.test.js`) to Vitest, improving maintainability.
- Removed `tsconfig.json` and related TypeScript loaders from `webpack` configurations (`webpack.dev.js`, `webpack.prod.js`).
- Adjusted `eslint.config.mjs` to support Vitest tests.
- Updated `package-lock.json` to include Vitest, test utilities (`jsdom`, `@vue/test-utils`), and other associated packages.
- Updated Nginx configuration for better compression on assets (`gzip` adjustments).
- Enhanced `entrypoint.sh` to include first-run library indexing (`--if-empty` argument).
- Simplified the `scan_comics` command with a dedicated test for empty database scans.

This transition improves testing workflows and backend/frontend synergy while removing unused TypeScript dependencies.

frontend/webpack.prod.js

@@ -11,7 +11,9 @@ module.exports = (env = {}) => {
   return {
 
     mode: 'production',
-    devtool: 'hidden-source-map',
+    // No source maps in production: they are not served to browsers, but collectstatic
+    // copies them into /static/ so browser devtools would pull ~3.3 MiB of maps.
+    devtool: false,
     entry: path.resolve(__dirname, './src/main.js'),
     output: {
       path: path.resolve(__dirname, './dist/bundles/'),
@@ -22,14 +24,6 @@ module.exports = (env = {}) => {
           test: /\.vue$/,
           use: 'vue-loader'
         },
-        {
-          test: /\.ts$/,
-          loader: 'ts-loader',
-          options: {
-            appendTsSuffixTo: [/\.vue$/],
-            transpileOnly: true
-          }
-        },
         {
           test: /\.css$/,
           use: [MiniCssExtractPlugin.loader, "css-loader"],