web/NPM Workspaces: ESbuild version cleanup (#14541)

* web: Check JS files. Add types.

* web: Fix issues surrounding Vite/ESBuild types.

* web: Clean up version constants. Tidy types

* web: Clean up docs, types.

* web: Clean up package paths.

* web: (ESLint) no-lonely-if

* web: Render slot before navbar.

* web: Fix line-height alignment.

* web: Truncate long headers.

* web: Clean up page header declarations. Add story. Update paths.

* web: Ignore out directory.

* web: Lint Lit.

* web: Use private alias.

* web: Fix implicit CJS mode.

* web: Update deps.

* web: await all imports.

web/bundler/mdx-plugin/node.js

@@ -0,0 +1,83 @@
+/**
+ * @file MDX plugin for ESBuild.
+ *
+ * @import {
+ *   OnLoadArgs,
+ *   OnLoadResult,
+ *   Plugin,
+ *   PluginBuild
+ * } from "esbuild"
+ */
+import * as fs from "node:fs/promises";
+import * as path from "node:path";
+
+/**
+ * @typedef {Omit<OnLoadArgs, 'pluginData'> & LoadDataFields} LoadData
+ *   Data passed to `onload`.
+ *
+ * @typedef LoadDataFields
+ *   Extra fields given in `data` to `onload`.
+ * @property {PluginData | null | undefined} [pluginData]
+ *   Plugin data.
+ *
+ *
+ * @typedef PluginData
+ *   Extra data passed.
+ * @property {Buffer | string | null | undefined} [contents]
+ *   File contents.
+ */
+
+const name = "mdx-plugin";
+
+/**
+ * @typedef MDXPluginOptions
+ *
+ * @property {string} root Root directory.
+ */
+
+/**
+ * Bundle MDX into JSON modules.
+ *
+ * @param {MDXPluginOptions} options Options.
+ * @returns {Plugin} Plugin.
+ */
+export function mdxPlugin({ root }) {
+    return { name, setup };
+
+    /**
+     * @param {PluginBuild} build
+     *   Build.
+     * @returns {undefined}
+     *   Nothing.
+     */
+    function setup(build) {
+        build.onLoad({ filter: /\.mdx?$/ }, onload);
+
+        /**
+         * @param {LoadData} data
+         *   Data.
+         * @returns {Promise<OnLoadResult>}
+         *   Result.
+         */
+        async function onload(data) {
+            const content = String(
+                data.pluginData &&
+                    data.pluginData.contents !== null &&
+                    data.pluginData.contents !== undefined
+                    ? data.pluginData.contents
+                    : await fs.readFile(data.path),
+            );
+
+            const publicPath = path.resolve(
+                "/",
+                path.relative(path.join(root, "website"), data.path),
+            );
+            const publicDirectory = path.dirname(publicPath);
+
+            return {
+                contents: JSON.stringify({ content, publicPath, publicDirectory }),
+                loader: "file",
+            };
+        }
+    }
+}