Add golden regression for OVRTX GPU transform rendering

[mataylor-nvidia]

Description

Reading GPU transforms with OVRTX 0.4 can intermittently corrupt textures in one of several camera outputs. Add a native GPU rendering regression that detects this corruption and passes with OVRTX 0.5.0.377615.

The test renders two 640 × 360 cameras, moves a sphere and cube over a checkerboard, then compares each of the final ten settled RGB frames with checked-in GPU-off golden images. Both cameras are checked because the affected render product can vary between processes. It uses the existing OVRTX pixel tolerance (RGB L2 > 10, at most 3% differing pixels), supports both output-key APIs, and saves failure images and renderer logs.

Includes a local USD fixture, Git LFS golden PNGs, reference provenance/regeneration instructions, and a test-only changelog fragment. Requires the existing ovrtx and test extras plus an RTX-capable CUDA GPU; no Isaac Sim runtime or remote scene assets.

Draft / merge dependency: the repository still pins OVRTX 0.4.1.364340. This test intentionally fails with that runtime; it has no version-based skip or xfail. The dependency upgrade must be coordinated before merging. This PR does not change the runtime pin.

Validation

NVIDIA A40, driver 580.173.02. Maximum differing-pixel percentage across both cameras and all ten comparison frames; limit 3%:

Runtime	GPU transform reads	Result	Maximum difference
0.4.1.364340	Enabled	Failed as intended	20.14%
0.4.1.364340	Disabled, control capture	Passed	1.85%
0.5.0.377615	Enabled	Passed	0.52%
0.5.0.377615	Enabled, independent repeat	Passed	0.50%

• uv run --frozen --no-sync python -m pytest source/isaaclab_ov/test/test_ovrtx_gpu_transforms_golden.py -q: verified the 0.4 failure.
• Same command with the verified 0.5 SDK on PYTHONPATH: passed in two independent processes.
• uv run --frozen --no-sync isaaclab -f: passed all repository pre-commit checks, including Git LFS pointers and changelog validation.
• UV_FROZEN=1 uv run --isolated --extra test -- make -C docs current-docs: unsuccessful. Source validation reported 14 duplicate object-description warnings from unchanged isaaclab.sim.schemas.schemas_cfg API documentation; the remaining HTML/code-highlighting generation was stopped after those warnings. The new test-fixture README is outside the Sphinx documentation tree.

link to comparison gif, too large to upload to PR:

https://nvidia.enterprise.slack.com/files/U0724PHG22F/F0C2DPK9AHY/camera_1_comparison.gif

Type of change

• Regression test and test-fixture documentation

Release backport

• Backport to the active release branch

Checklist

• Read the contribution guidelines
• Ran repository formatting and pre-commit checks
• Documented the fixture, reference provenance, and regeneration process
• Warning-free documentation build (existing duplicate API-description warnings noted above)
• Verified that the regression fails with 0.4 and passes with 0.5
• Added a .skip changelog fragment for the touched package
• Contributor already listed in CONTRIBUTORS.md