chore(runtime): set exports field in client runtime package.json (#5842)

* chore(runtime): set exports field in client runtime package.json

* fix package.json

* prettier

* extend export

* extend export

package.json

@@ -22,6 +22,34 @@
     "sys/",
     "testing/"
   ],
+  "exports": {
+    ".": {
+      "import": "./internal/stencil-core/index.js",
+      "require": "./internal/stencil-core/index.cjs"
+    },
+    "./internal": {
+      "import": "./internal/index.js"
+    },
+    "./internal/client": {
+      "import": "./internal/client/index.js"
+    },
+    "./internal/testing": {
+      "import": "./internal/testing/index.js"
+    },
+    "./internal/testing/*": {
+      "import": "./internal/testing/*"
+    },
+    "./internal/app-data": {
+      "import": "./internal/app-data/index.js",
+      "require": "./internal/app-data/index.cjs"
+    },
+    "./compiler": {
+      "import": "./compiler/stencil.js"
+    },
+    "./compiler/*": {
+      "import": "./compiler/*"
+    }
+  },
   "scripts": {
     "build": "npm run clean && npm run tsc.prod && npm run ts scripts/index.ts -- --prod --ci",
     "build.watch": "npm run build -- --watch",

scripts/esbuild/internal-platform-client.ts

@@ -32,7 +32,9 @@ export async function getInternalClientBundles(opts: BuildOptions): Promise<ESBu
     name: '@stencil/core/internal/client',
     description:
       'Stencil internal client platform to be imported by the Stencil Compiler and internal runtime. Breaking changes can and will happen at any time.',
-    main: 'index.js',
+    exports: './index.js',
+    main: './index.js',
+    type: 'module',
     sideEffects: false,
   });