Add Sentry monitoring for FastAPI and Langchain errors

Add Sentry for

• https://docs.sentry.io/platforms/python/integrations/langchain/
• https://docs.sentry.io/platforms/python/integrations/fastapi/

added In Progress label

assigned to @gridinoc

mentioned in merge request !14 (merged)

added In Progress (Under Review) label and removed In Progress label

added Done & Cleared label and removed In Progress (Under Review) label

closed