Multi-page Streamlit: shared ui.py, pages for Clauses/Negotiation/Chat/Downloads

Enhanced demo: 12 realistic clauses covering all severity levels and clause types

Restructure: clauseguard as package subfolder, app_file: clauseguard/app.py

Add Hugging Face Spaces metadata

ClauseGuard: AI contract analysis with Qwen2.5 via vLLM on AMD

initial commit