feat(language-gate): detect non-English queries and return polite response

fix(critical): identity leak, intent misclassification, reranker tokenizer

fix(prompt): prevent hallucinated citations - enforce strict source index

fix(rag-api): session ID merging + FOLLOW_UP streaming leak

fix(rag-api): relax keyword overlap filter + cache DeBERTa intent results

feat: numbered citations [1][2][3], follow-up questions, focus modes

feat: Add query enhancements and flexible prompting (v2.1)

fix: make _build_context and execute_chat async for hybrid search

fix: use await instead of asyncio.run for hybrid search

fix: add missing logger import in rag_chat_use_case

feat(rag): implement hybrid search with live sources and production-grade intent classification