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

Show warnings in Arena columns when retrieved chunks lists are empty

Replace Gemma embedding model with BAAI/bge-small-en-v1.5 and cache at build time

Optimize referee model to Qwen2.5-0.5B-Instruct for CPU and add warning popup

Configure for 100% self-contained CPU deployment

Few tweaks

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

changes for readme file and UI changes

initial: RAG Visualizer (Phases 1-4)

local: phase 5 arena and text highlighter