refactor: use separate prefix for esm package entries

Author: antongolub

package.json

@@ -28,7 +28,6 @@
     ".": {
       "types": "./dist/index.d.ts",
       "node": {
-        "import": "./browser/index.js",
         "require": "./dist/index.js"
       },
       "default": "./browser/index.js"
@@ -37,10 +36,17 @@
     "./util": {
       "types": "./dist/util.d.ts",
       "node": {
-        "import": "./browser/dist/util.js",
         "require": "./dist/util.js"
       },
       "default": "./browser/dist/util.js"
+    },
+    "./esm": {
+      "types": "./dist/index.d.ts",
+      "default": "./browser/index.js"
+    },
+    "./esm/util": {
+      "types": "./dist/util.d.ts",
+      "default": "./browser/dist/util.js"
     }
   },
   "scripts": {