sync: today's source updates (XML-only prompt, reward unclip, neg-reward on loss, pinned versions, configs reorg)

fix: incremental log writes, openenv.yaml descriptions, openai dep

feat: mount Gradio UI in OpenEnv app

feat: add YAML config for server and runners

chore: add OpenEnv submission files (Dockerfile, validate, uv.lock)

push

Initial commit: CricketCaptain-LLM OpenEnv RL environment