[CI unblock] Skip viewergl-fully-black test + fix warp intersphinx 404

[hujc7]

Summary

Two unrelated CI breakages on develop, bundled here so develop turns green in one PR.

1. Skip the failing viewergl test

test_cartpole_newton_visualizer_viewergl_rgb_motion[physx,newton] started returning all-black frames on develop after nvcr.io/nvidian/isaac-sim:latest-develop flipped to a Kit 110.1.1 + USD 25.11 base. The failure has been deterministic across multiple PRs (#5523, #5495, #5408, …).

Investigation so far has ruled out:

• PR use RendererCfg as default renderer_cfg in CameraCfg #5521 (revert in [DO NOT MERGE] Test revert of PR #5521 to isolate viewergl failure #5539 still failed)
• Newton 1.0 → 1.2.0rc2 viewer code regression (only 7-line addition; ViewerGL alone yields 1.08M nonzero pixels)
• warp 1.12 → 1.13 RegisteredGLBuffer ABI (byte-identical)
• Module-load side effects of isaaclab_physx.renderers
• CUDA-GL interop (PR [debug] Instrument ViewerGL.get_frame for fully-black diagnosis #5540 diagnostic confirms direct CPU FBO readback also returns zeros, with GL_NO_ERROR)
• GL context-currency (PR [H6 fix attempt] Make Newton ViewerGL context current before get_frame #5541 H6 attempt: still fails)
• GL/CUDA sync (PR [H4 fix attempt] Add explicit glFinish + wp.synchronize_device before PBO map #5542 H4 attempt: still fails)

Diagnostic output (PR #5540 v2):

[VIZDIAG] fbo=c_uint(8)  pbo=None  size=600x600
[VIZDIAG] glGetError before: GL_NO_ERROR
[VIZDIAG] CPU-readback: nonzero=0/1080000  max=0  err=GL_NO_ERROR
[VIZDIAG] PBO-result: nonzero=0/1080000  max=0

The FBO itself is empty — Newton's pyglet/EGL renderer is not depositing pixels under Kit 110.1.1, even though tiled_camera_rgb_non_black (Kit RTX path) on the same env passes. Underlying root cause still being chased; this PR ships the skip to unblock develop.

2. Fix warp intersphinx 404 in docs build

https://nvidia.github.io/warp/objects.inv started returning 404 — Warp's objects.inv only lives at /stable/ and /latest/ now. With Sphinx's warnings_treated_as_errors, the broken intersphinx fetch fails the docs build on every PR. Pinning to /stable/ (matches the existing PyTorch /docs/2.11/ workaround pattern in the same file).

Verified https://nvidia.github.io/warp/stable/objects.inv returns 200.

Test plan

• CI isaaclab_visualizers on this branch — was passing earlier with the skip; will re-verify with the bundled docs fix
• CI Build Latest Docs on this branch — must turn green (was failing on every recent PR before this fix)

Re-enable plan

Once the underlying viewergl bug is identified and fixed, drop the @pytest.mark.skip decorator and remove the jichuanh-disable-viewergl-flaky.skip fragment.

[greptile-apps]

Greptile Summary

This PR skips test_cartpole_newton_visualizer_viewergl_rgb_motion (both physx and newton parametrizations) while a root cause for the deterministic all-black ViewerGL.get_frame output in CI is investigated. An empty .skip changelog fragment is also added to avoid a version bump for the test-only change.

• @pytest.mark.skip is placed above @pytest.mark.parametrize, which correctly propagates the skip to all parametrized variants; no test logic is changed.
• Investigation evidence in the PR description rules out several false leads (Newton rc1→rc2 diff, warp API change, pure flakiness) and points to a CUDA-OpenGL interop init-order fragility as the likely cause.

Confidence Score: 5/5

Safe to merge — a single skip decorator is added to one test function; no production code is touched.

The change is limited to adding @pytest.mark.skip above @pytest.mark.parametrize, which is the correct placement to skip all parametrized variants. The empty changelog fragment follows established project convention. No logic, APIs, or production paths are affected.

No files require special attention.

Important Files Changed

Filename	Overview
source/isaaclab_visualizers/test/test_visualizer_cartpole_integration.py	Adds @pytest.mark.skip above @pytest.mark.parametrize on test_cartpole_newton_visualizer_viewergl_rgb_motion; both [physx,newton] and [newton,newton] variants will be skipped correctly.
source/isaaclab_visualizers/changelog.d/jichuanh-disable-viewergl-flaky.skip	Empty changelog fragment with .skip extension; prevents a version bump for a test-only change, consistent with the precedent set in PR #5508.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["test_cartpole_newton_visualizer_viewergl_rgb_motion"] -->|"@pytest.mark.skip"| B["SKIPPED — both parametrizations"]
    B --> C["[physx, newton]"]
    B --> D["[newton, newton]"]
    C -.->|"pending root-cause fix"| E["Re-enable in follow-up PR"]
    D -.->|"pending root-cause fix"| E

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