fix: clamp inference score between 0.0001 and 0.9999 to pass strictly bounded validation

fix: make TiffinPackingEnvironment a singleton to support stateless HTTP endpoints in openenv

fix: remove pybullet, fix libgl1 for Docker build on HF Spaces

fix: restore top-level openai import and client init per sample format

fix: add structured output markers for validator

fix: resolve OpenEnv validation issues (entry point and uv.lock)

fix: add HF Spaces YAML frontmatter for Docker SDK

feat: complete tiffin packing OpenEnv environment with 3 tasks, VLM, grader, and inference