ci(docs): pull Git LFS assets before building docs

[jiwenc-nv]

Problem

Fixes #756. Docs images broke on the deployed site — most visibly on PR previews such as https://nvidia.github.io/IsaacTeleop/preview/pr-776/ — after #669 moved images into Git LFS (merged 2026-06-12).

The build-docs job checks out with actions/checkout@v6, which defaults to lfs: false. So the working tree holds LFS pointer files (~131-byte text stubs), Sphinx copies them verbatim into _images/, and peaceiris/actions-gh-pages pushes the stubs to gh-pages. Browsers then receive version https://git-lfs.github.com/spec/v1 … instead of an image.

Verified empirically: preview/pr-776/_images/isaac-teleop-hero.jpg is served as a 131-byte pointer, and all 23 LFS-tracked docs images are pointers in the source tree. Production main/ still renders only because that path is stale (last deployed before the migration, kept by keep_files: true); the next main docs deploy would overwrite it with pointers.

The muzimuzhi symlink/tarring theory in the issue does not apply here — that failure mode is specific to native GitHub Pages artifact deploys, whereas this repo pushes real files via actions-gh-pages.

Fix

• lfs: true on the build-docs checkout — materializes the assets for current-docs, which is exactly what PR previews deploy.
• git lfs fetch --all before make multi-docs — lfs: true only fetches HEAD's objects, but sphinx-multiversion checks out each ref (main, release/*, v* tags) into its own worktree, so those refs' LFS objects must be in the local cache to smudge real files.

build-app is intentionally left unchanged: git ls-files finds no LFS-tracked raster images in webxr_client, and its SVG icons are explicitly LFS-excluded in .gitattributes.

Verification

Workflow edits are only fully provable via a CI run. Since docs.yaml's pull_request trigger runs from the PR branch, this PR itself (which touches .github/workflows/docs.yaml) exercises the edited workflow — confirm that preview/pr-<N>/_images/*.jpg serves binary rather than a pointer stub.

Summary by CodeRabbit

• Documentation
  • Improved documentation builds to include the correct media assets across all published documentation versions.
  • Resolved issues where images and other large files could appear as missing or invalid placeholders.

[github-actions]

📝 Docs preview is not auto-deployed for fork PRs.

A maintainer with write access to NVIDIA/IsaacTeleop can deploy a preview by
commenting /preview-docs on this PR. Once deployed, the preview
will live at:

https://nvidia.github.io/IsaacTeleop/preview/pr-777/

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: c40795cb-4a6f-4a5c-ad5a-f32d97353315

📥 Commits

Reviewing files that changed from the base of the PR and between a6d606e and 8e381bd.

📒 Files selected for processing (1)

• .github/workflows/docs.yaml

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📝 Walkthrough

Walkthrough

The build-docs workflow checkout now enables Git LFS, ensuring documentation packaging receives actual media files. Before multi-version documentation generation, the workflow also runs git lfs fetch --all to retrieve LFS objects for all processed refs.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main workflow change: fetching Git LFS assets before the docs build.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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