Fix docs build broken by sphinx-argparse commands domain

[jambayk]

Describe your changes

sphinx-argparse 0.6.0 registers a commands domain (ArgParseDomain) that does not implement the standard Sphinx Domain.resolve_any_xref API. MyST falls back to calling the domain's resolve_xref for every markdown cross-reference, and that method logs Error, no command xref target from ... for each target it doesn't own, including links that already resolve via doc/std resolution. Under -W, this flood of warnings fails the docs build.

This adds a resolve_any_xref implementation to ArgParseDomain in docs/source/conf.py, supplying the API the extension omits so MyST resolves real command targets and skips the noisy fallback. This also removes the myst.domains legacy-domain warning, so the earlier suppress_warnings entry for it is dropped. No version pin is added to docs/requirements.txt.

The rendered HTML is byte-identical to before; only the spurious warnings are gone. The sphinx-build -W build passes.

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.

(Optional) Issue link

[Copilot]

Pull request overview

Updates the Sphinx documentation configuration to silence a specific class of MyST-Parser warnings during docs builds, reducing noise from known/expected warnings in the Olive docs pipeline.

Changes:

• Extends suppress_warnings in docs/source/conf.py to include myst.domains alongside the existing myst.xref_missing suppression.