fix(mcp): preserve default temperature for non-openai llms

[fengfeng-zi]

Summary

• stop overriding Graphiti core's default temperature when MCP config leaves temperature unset for Anthropic, Gemini, and Groq providers
• keep explicit temperature overrides intact
• add focused factory regression tests for unset and explicit temperature behavior

Testing

• .venv\Scripts\python.exe -m pytest mcp_server\tests\test_factories.py -q

Closes #1103

[danielchalef]

Thanks for this — you correctly diagnosed that the MCP factory sends temperature=None to the non-OpenAI clients (Anthropic/Gemini/Groq), which pass it to their APIs verbatim and 400 (#1103). I've reimplemented the fix directly on main as #1570 (this branch was CI-red and behind), using the same omit-when-unset approach with a parametrized test across all three providers. Closing as superseded by #1570 — credit to you for the fix.