Build GitHub release JavaScript also into package

This runs the Rollup build for our GitHub release JavaScript `govuk-frontend-{{ version }}.min.js` into package too but without the version number

packages/govuk-frontend/tasks/build/package.test.mjs

@@ -83,6 +83,15 @@ describe('packages/govuk-frontend/dist/', () => {
         join(requirePath, `${name}.bundle.mjs.map`) // with source map
       ]))
 
+      // Only main package entry is compiled to minified ES module bundle
+      .flatMap(mapPathTo(['**/govuk/all.mjs'], ({ dir: requirePath }) => [
+        join(requirePath, 'all.mjs'),
+
+        // ES module bundles for browsers, minified
+        join(requirePath, 'govuk-frontend.min.js'), // avoid .mjs extension MIME issues
+        join(requirePath, 'govuk-frontend.min.js.map') // with source map
+      ]))
+
       // Add Autoprefixer prefixes to all source '*.scss' files
       .flatMap(mapPathTo(['**/*.scss'], ({ dir: requirePath, name }) => [
         join(requirePath, `${name}.scss`),

packages/govuk-frontend/tasks/scripts.mjs

@@ -1,5 +1,6 @@
 import { join, resolve } from 'path'
 
+import { pkg } from 'govuk-frontend-config'
 import { configs, scripts, npm, task } from 'govuk-frontend-tasks'
 import gulp from 'gulp'
 
@@ -22,6 +23,25 @@ export const compile = (options) => gulp.series(
     })
   ),
 
+  /**
+   * Compile GOV.UK Frontend JavaScript (minified) for main entry point only
+   */
+  task.name("compile:js 'minified'", () =>
+    scripts.compile('**/all.mjs', {
+      ...options,
+
+      srcPath: join(options.srcPath, 'govuk'),
+      destPath: join(options.destPath, 'govuk'),
+      configPath: join(options.basePath, 'rollup.release.config.mjs'),
+
+      // Rename using package name and `*.min.js` extension due to
+      // web server ES module `*.mjs` Content-Type header support
+      filePath ({ dir, name }) {
+        return join(dir, `${name.replace(/^all/, pkg.name)}.min.js`)
+      }
+    })
+  ),
+
   /**
    * Compile GOV.UK Prototype Kit config
    */