Update React Editor integration and clean up template

app/collections/editor/page.tsx

@@ -1,9 +1,6 @@
 import PageEditor from '@/components/page-editor';
 import pageData from '../page.json';
 
-// Editor for /collections. Sitting under the route it edits means the preview
-// resolves the same params the public page gets, and `../page.json` is the
-// very file publishing writes back to.
 export default function EditorPage() {
-  return <PageEditor routeKey="/collections" page={pageData} />;
+  return <PageEditor pagePath="app/collections/page.json" page={pageData} />;
 }