LiteLLM expects the 'zai/' provider prefix for Zhipu AI (Z.ai) models,
not 'zhipu/'. This was causing 'LLM Provider NOT provided' errors when
users configured models like 'glm-4.7' without an explicit prefix.
According to LiteLLM docs, the correct format is:
- model='zai/glm-4.7' (correct)
- NOT model='zhipu/glm-4.7' (incorrect)
This fix ensures auto-prefixed models use the correct 'zai/' format.
Fixes: Error when using Zhipu AI models with shorthand names like 'glm-4.7'
