fix(envhub): durable HUD smoke markers + writable contract path

fix(envhub): unwrap gym wrappers + keep sim alive through settle/step

fix(envhub): unwrap gym wrappers + keep sim alive through settle/step

fix(envhub): unwrap gym wrappers + keep sim alive through settle/step

fix(envhub): unwrap gym wrappers + keep sim alive through settle/step

fix(envhub): unwrap gym wrappers + keep sim alive through settle/step

Materialize HF blob symlinks so USD/PhysX see real .usd files

Add EnvHub/HUD smoke scripts

Update hud_env module purge

Fix asset paths under HF Hub blob symlinks (use Path.absolute)

Remove accidental __pycache__ from EnvHub package

Add HF model card metadata

Initial EnvHub package: assembly_bench for Isaac Lab Arena

initial commit