Feat: add basic Langfuse support for LLM module (#6443)

### What problem does this PR solve?

#6155

Add basic Langfuse support for LLM module.

A trace example:

<img width="755" alt="image"
src="https://github.com/user-attachments/assets/25c1f852-5116-486c-a47f-6097187142ca"
/>


### Type of change

- [x] New Feature (non-breaking change which adds functionality)

pyproject.toml

@@ -124,6 +124,7 @@ dependencies = [
     "flasgger>=0.9.7.1,<0.10.0",
     "xxhash>=3.5.0,<4.0.0",
     "trio>=0.29.0",
+    "langfuse>=2.60.0",
 ]
 
 [project.optional-dependencies]