fix(devcontainer): reset /env ownership on attach so uv sync can upgrade

Running commands like sudo juice install leaves root-owned pycache directories in /env/.venv. The ownership reset only ran on container creation, so after a container restart uv sync --upgrade in postAttachCommand failed with "failed to remove directory ... pycache: Permission denied". Run configure_env_dir on every attach.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com