build: enhance Terser configuration for production minification

- Update Terser options to enable top-level mangling and increase compression passes from 2 to 3.
- Improve minification by dropping unused top-level variables and functions.

vite.config.ts

@@ -100,8 +100,9 @@ export default defineConfig(({ mode }) => {
       minify: isProduction ? "terser" : false,
       ...(isProduction && {
         terserOptions: {
-          compress: { passes: 2 },
-          mangle: true,
+          toplevel: true, // Mangle top-level names and drop unused top-level vars/functions
+          compress: { passes: 3 },
+          mangle: { toplevel: true }, // Shorten top-level function/variable names
           format: {
             comments: false,
           },