Clamp all remaining score leak paths: /state, step_rewards, demo SSE

Fix reward.value to always be task_score in (0,1) exclusive

fix

fix

Fix IndexError: skip empty-choices chunks from HF Router streaming

fix: default LLM to HF Router + Qwen2.5-72B, no custom Space variables needed

Initial submission: SQL Agent OpenEnv for Meta+HF hackathon