feat: AI search endpoint via LiteLLM

[PierreBrisorgueil]

Summary

Add AI-powered documentation search endpoint using LiteLLM proxy.

Details

• Create modules/docs/ module (routes, controller, service)
• POST /api/docs/search — accepts query, returns AI-generated answer with source references
• Uses LiteLLM proxy at lllm.pierreb.me for model abstraction
• Indexes OpenAPI spec + guide content for RAG context
• Module respects activated flag

Phase 8 — Developer Docs (Step 5)

[PierreBrisorgueil]

Deferred — AI search not needed in the stack for now