Langfuse v4 Adds Observability Tracing for RAG and AI Agents

Langfuse v4, an open-source observability tool, now supports tracing for RAG and agent workflows, recording execution time and I/O for each step. The update deprecates older APIs like langfuse_context and update_current_trace, requiring users to adapt to v4.9+. Developers can integrate it via a @observe() decorator and monitor costs and latency on a dashboard.