set preserveModules: true for CJS build, too

Author: dynst

rollup.config.mjs

@@ -53,9 +53,12 @@ const MAIN_BUNDLE_CONFIG = {
   input: "lib/index.ts",
   output: [
     {
-      file: "dist/index.cjs",
       name: "hashwasm",
       format: "umd",
+      entryFileNames: "[name].cjs",
+      preserveModules: true,
+      preserveModulesRoot: "lib",
+      dir: "dist",
     },
     {
       format: "es",