chore(cloudxr): bump runtime SDK version to 6.3.0-rc2

[jiwenc-nv]

Description

Bumps CXR_RUNTIME_SDK_VERSION 6.2.1 → 6.3.0-rc2 (NGC cloudxr-dev/cloudxr-runtime-binary:6.3.0-rc2-public), matching CXR_WEB_SDK_VERSION, at 6.3.0-rc2 since #841. Nothing compiles or links against the SDK — CMake extracts the tarball and bundles only the shared objects — so the pin is the whole change.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Dependency bump; none of the above apply.

Testing

CI only. Setup CloudXR SDK passed on all 12 build jobs (x64 and arm64), and the test-cloudxr matrix exercises the 6.3 runtime end to end on the self-hosted GPU runners, covering the OpenXR extensions vendored in deps/cloudxr/openxr_extensions/.

Checklist

• I have read and understood the contribution guidelines
• I have run the linter and formatter with SKIP=check-copyright-year pre-commit run --all-files
• I have made corresponding changes to the documentation
• I have added tests that prove my fix/feature works (or explained why not) — no test surface for a version pin
• I have signed off all my commits (git commit -s) per the DCO

[coderabbitai]

📝 Walkthrough

Walkthrough

The default CloudXR runtime SDK version changes from 6.2.1 to 6.3.0-rc2 in the environment configuration.

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

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the CloudXR runtime SDK version bump from 6.2.1 to 6.3.0-rc2.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch jiwenc/cloudxr-runtime-6.3.0-rc2

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