fix(local_hammer_nail): make the board/nail USDs render, and publish the wall variant
The hammer board+nail have never been visible in an IsaacSim render. Three independent
defects in the UrdfConverter output, each silent (no error, nothing drawn):
Geometry lived at ROOT (/visuals, /colliders) while defaultPrim is /board_nail*, and
/wall/visuals only held an internal reference </visuals/wall>. A scene REFERENCES the
asset, which composes only the defaultPrim subtree, so the internal ref dangled and the
visuals composed empty. Measured referenced-gprims: 0 (ArtVIP cabinet_12, for contrast: 181).
Fixed by flattening so geometry is inlined under the default prim -> 5.Stale extents: unit primitives (Cube.size=1.0, real size from the parent xformOp:scale)
carrying the ALREADY-SCALED extent +/-(0.03,0.15,0.15). Extent is local-space, so bounds
were 16.7x too small in x — and Hydra culls on bounds. Live-stage bbox went from
0.004x0.09x0.09 to the authored 0.06x0.30x0.30.Zero Material prims — the brick texture and steel colours were dropped entirely, so
everything rendered flat grey. Added UsdPreviewSurface materials (brick texture; steel at
metallic 1.0 / roughness 0.22) and rebuilt the wall's Cube as a UV-mapped Mesh, since
UsdGeom.Cube carries no UVs for a texture to map to.
Defects 1 and 2 affect the previously published board_nail.usd as well, so it is updated here.
Also publishes the hammer_insert_nail_wall variant, which was absent from this repo entirely
(board_nail_wall.xml / .urdf / textures/wall_brick.png / the USD set) — without the MJCF a
fresh checkout cannot run the task even in MuJoCo.
Verified on isaac5_venv (Isaac Sim 5.0.0.0, driver 580.167.08): RealTimePathTracing + DLSS
render shows the brick wall and the metal nail; reference-composition test 0 -> 5 gprims.