[FEATURE] Run LangChain in the client side instead of server side

[badbye]

Describe the feature you'd like LangChain can be used in the browser. I think this whole project could work without a server.

[HenryHengZJ]

Yeah it works on browser now but not sure what's the limitation there.

For now we'd prefer to stick to using server for NodeJS thread processing, serve api and flow logic, connecting to databases for your chatflows and messages (we'll add postgres, sql). Most npm dependencies used are also designed for Node