Fix emoji in README

Update README with HF Space metadata

Finalizing CodeArena RL Benchmark: frontend improvements, GRPO training scripts, and cleaned environment

docs: Rewrite README for hackathon submission

Complete all tasks: Adaptive curriculum, GRPO, React frontend, LLM-as-a-judge

Production-ready: add server/app.py with fallback-safe /reset, fix Dockerfile, add HF metadata, add task JSON files

Initial commit