Add chat memory

[sinedied]

Currently only the last chat message with the user question is fed to the chat model. However, the complete chat history is sent to the server. We should use LangChain's Memory component to integrate the previous messages in the model invocation, with a limit set.

Tasks

• Add BufferMemory with the last 5 messages to the existing chain in /chat endpoint
• Extract the 5 message window value in constants.ts

Superseded by #106 that implements full chat history

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this issue will be closed.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this issue will be closed.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this issue will be closed.

[github-actions]

This issue was closed because it has been stalled for 7 days with no activity.