chore: maintain CSS output file name in [email protected]

Without this change, build would fail because the produced stylesheet assumes
the `package.json['name']` i.e., `styles/rrweb.css`. To maintain the existing
behavior, these changes are required.

See https://vite.dev/guide/migration.html#customize-css-output-file-name-in-library-mode

Author: ruiconti

packages/rrweb/package.json

@@ -45,6 +45,7 @@
         "default": "./dist/rrweb.cjs"
       }
     },
+    "./dist/rrweb.css": "./dist/rrweb.css",
     "./dist/style.css": "./dist/style.css"
   },
   "files": [

vite.config.default.ts

@@ -115,6 +115,7 @@ export default function (
     build: {
       // See https://vitejs.dev/guide/build.html#library-mode
       lib: {
+        cssFileName: 'style',
         entry,
         name,
         fileName,
@@ -133,12 +134,6 @@ export default function (
       minify: false,
 
       sourcemap: true,
-
-      // rollupOptions: {
-      //   output: {
-      //     manualChunks: {},
-      //   },
-      // },
     },
     plugins: [
       dts({