Fix grader: save WS episodes to _completed, fix episode_id in _grade

Clamp grader scores to (0.001, 0.999) — validator requires strictly (0, 1)

Fix Docker base image tag and sync success_criteria across files

Fix /reset to accept empty/null body from automated checker

Fix uvicorn app reference to avoid server/ package shadowing server.py

Complete OpenEnv hackathon submission

Initial Commit