feat!: convert source to native ES modules with dual ESM/CJS build

.changeset/config.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://unpkg.com/@changesets/config@3.1.2/schema.json",
-  "changelog": ["./changelog-generator.mjs", { "repo": "webpack/sass-loader" }],
+  "changelog": ["./changelog-generator.js", { "repo": "webpack/sass-loader" }],
   "fixed": [],
   "linked": [],
   "access": "public",

.changeset/esm-conversion.md

@@ -0,0 +1,8 @@
+---
+"sass-loader": major
+---
+
+Convert source to native ECMAScript modules. The package now declares
+`"type": "module"` and exposes both an ESM and a CommonJS build via the
+`exports` field. CommonJS consumers continue to work via `require`, and
+ESM consumers can now `import` the loader directly.

babel.config.js

@@ -0,0 +1,30 @@
+const MIN_BABEL_VERSION = 7;
+
+export default (api) => {
+  api.assertVersion(MIN_BABEL_VERSION);
+
+  const env = api.env();
+  const isCjs = env === "cjs";
+
+  return {
+    presets: [
+      [
+        "@babel/preset-env",
+        {
+          targets: { node: "22.11.0" },
+          modules: false,
+        },
+      ],
+    ],
+    plugins: isCjs
+      ? [
+          [
+            "@babel/plugin-transform-modules-commonjs",
+            {
+              ignoreDynamicImport: true,
+            },
+          ],
+        ]
+      : [],
+  };
+};

eslint.config.js

@@ -0,0 +1,8 @@
+import { defineConfig } from "eslint/config";
+import configs from "eslint-config-webpack/configs.js";
+
+export default defineConfig([
+  {
+    extends: [configs["node-recommended"]],
+  },
+]);

lint-staged.config.js

@@ -1,6 +1,4 @@
-"use strict";
-
-module.exports = {
+export default {
   "*": [
     "prettier --cache --write --ignore-unknown",
     "cspell --cache --no-must-find-files",