Add mobile responsive CSS styles for grid columns, header, and Arena modal

Configure for 100% self-contained CPU deployment

RAG retreival updates

Restore Phase 5 advanced RAG changes and clean schemas.py

Merge branch 'main' into feature/advanced-rag

Pushing the changes for judge as LLM

initial: RAG Visualizer (Phases 1-4)

local: phase 5 arena and text highlighter