Add EvalView – open-source AI agent testing framework to README

[hidai25]

Adding EvalView, an open-source agent testing framework :

• Write YAML tests for LangGraph, CrewAI, OpenAI Assistants, Anthropic, custom APIs, etc.
• Assert exact tool calls, LLM-as-judge output quality, cost & latency thresholds
• Record real sessions → auto-generate hundreds of regression tests in minutes
• No DB needed for local/CI runs

Already hit 4k+ views in a few hours on r/LangChain:
https://www.reddit.com/r/LangChain/comments/1pe3ivc/how_i_stopped_langgraph_agents_from_breaking_in/

Thanks for maintaining the list. This fits perfectly under Testing & Evaluation