fix: reduce max_citations_total=10, retrieve_k=15, rerank_top_k=10 + filter chunks <50 chars

feat: remove per-doc citation cap, bump rerank_top_k=20, max_citations_total=50, expose all retrieved citations

fix: retrieve_k=20, strengthen system prompts to prevent citation hallucination, add _sanitize_citations post-processing

perf: revert to all-MiniLM-L6-v2, query embed cache, fire-and-forget Cloudinary, pre-warm reranker, reduce top-k

perf: upgrade embedding to all-mpnet-base-v2, add cross-encoder reranker, LRU cache, enable PII by default

fix: correct Inception API base URL (inceptionlabs.ai, not inception.ai)

fix: add generic LLM_API_KEY/LLM_BASE_URL/LLM_MODEL for any OpenAI-compatible API; fall back from broken api.inception.ai

fix models.py: match Neon schema varchar sizes, add email unique constraint