chore: remove sessions.db from tracking, add to gitignore

chore: add HuggingFace Space frontmatter to README

docs: rewrite README with badges, benchmark table, architecture diagram, and charts overview

docs: add README, requirements, and engineering problems log

feat: add animated Streamlit evaluation dashboard

feat: add LLM-as-judge evaluator and benchmark runner

feat: add core LangGraph multi-agent pipeline