build: use Terser for production minification

- Add terser devDependency and set build.minify to "terser" in production
- Enable source maps only for non-production builds
- Disable minification for dev builds
- Terser options: mangle names, strip comments, 2 compress passes

package.json

@@ -78,6 +78,7 @@
     "sinon": "^21.0.1",
     "sinon-chai": "^4.0.0",
     "tailwindcss": "^4.1.18",
+    "terser": "^5.42.0",
     "tsconfig-paths": "^4.2.0",
     "typescript": "^5.7.2",
     "typescript-eslint": "^8.26.0",

vite.config.ts

@@ -96,6 +96,17 @@ export default defineConfig(({ mode }) => {
       outDir: "static", // Webpack outputs to 'static', assuming we want to keep this.
       emptyOutDir: true,
       assetsDir: "assets", // Sub-directory for assets
+      sourcemap: !isProduction, // Source maps for dev builds only
+      minify: isProduction ? "terser" : false,
+      ...(isProduction && {
+        terserOptions: {
+          compress: { passes: 2 },
+          mangle: true,
+          format: {
+            comments: false,
+          },
+        },
+      }),
       rollupOptions: {
         output: {
           manualChunks: {