ci: clean up and conventions (#52)

rollup.config.ts

@@ -0,0 +1,16 @@
+import commonjs from "@rollup/plugin-commonjs";
+import nodeResolve from "@rollup/plugin-node-resolve";
+import typescript from "@rollup/plugin-typescript";
+
+const config = {
+  input: "src/index.ts",
+  output: {
+    esModule: true,
+    file: "dist/index.js",
+    format: "es",
+    sourcemap: true,
+  },
+  plugins: [typescript(), nodeResolve({ preferBuiltins: true }), commonjs()],
+};
+
+export default config;