Switch to bundling with Rollup (#495)

rollup.config.js

@@ -0,0 +1,38 @@
+import { defineConfig } from "rollup";
+import commonjs from "@rollup/plugin-commonjs";
+import nodeResolve from "@rollup/plugin-node-resolve";
+import terser from "@rollup/plugin-terser";
+import json from "@rollup/plugin-json";
+import { transform } from "esbuild";
+import builtinModulesList from "builtin-modules";
+
+const builtinModules = new Set(builtinModulesList);
+
+export default defineConfig({
+  input: "src/index.ts",
+  output: {
+    dir: "dist",
+    format: "esm",
+  },
+  external: (id) => builtinModules.has(id),
+  plugins: [
+    nodeResolve({
+      preferBuiltins: false,
+    }),
+    json(),
+    commonjs(),
+    {
+      name: "esbuild",
+      async transform(code, id) {
+        if (!/\.(mts|cts|ts|tsx)$/.test(id)) {
+          return null;
+        }
+        const result = await transform(code, {
+          loader: "ts",
+        });
+        return result.code;
+      },
+    },
+    terser(),
+  ],
+});