docs: Stage 17 metadata filtering — evolution, decisions, architecture

docs: update architecture.md to reflect current shipped state (v1.3.0 stack)

docs: update all references Render → HF Spaces (Stage 12)

feat: Stage 8 — eval dashboard, mandatory web search, docs update

docs: update architecture and decisions for 2026-05-30 changes

feat: Migrate LLM to Groq, fix web search pipeline, add structured logging

feat: Add RAGAS eval, score passthrough, docs, and hybrid retrieval config