Add BI documentations for generate, chat APIs for OpenAI, Anthropic, Deepseek, Azure OpenAI, Mistral and Ollama

[SasinduDilshara]

Description

Add BI documentations with runnable chat and structured-generation examples for each supported LLM provider: OpenAI, Azure OpenAI, Anthropic, Mistral, Ollama, and DeepSeek: covers multi-turn chat API and typed output generation (generate API) patterns for each provider.

Version

No response

[anupama-pathirage]

Moving to docs repo