Add @langchain/core dependency and update imports***

***Update SidepanelRouting to use dark mode***
***Add image support to PlaygroundMessage component

src/loader/html.ts

@@ -1,5 +1,5 @@
 import { BaseDocumentLoader } from "langchain/document_loaders/base"
-import { Document } from "langchain/document"
+import { Document } from "@langchain/core/documents"
 import { compile } from "html-to-text"
 
 export interface WebLoaderParams {