fix(pyproject): remove asyncio from pip dependencies

[injaneity]

This draft supersedes PR #1914 and carries its one-line dependency fix onto the direct branch.

Removes asyncio from cua-agent runtime dependencies because it is part of the Python standard library and is not a package dependency.

Closes #1913

Validation:

• pyproject.toml parses successfully with tomllib
• git diff --check passes
• GitHub Actions checks pass

Attribution:

• Salvaged from #1914

[github-actions]

📦 Publishable packages changed

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

📦 Publishable packages changed

This comment is status-only. Editing it or adding task-list checkboxes cannot authorize a release.
Only owner-applied release:<service> labels can do that.

• ⏸️ pypi/agent — no owner-authorized release label

Ask the release owner to apply release:<service> labels to auto-release on merge (+ optional bump:minor or bump:major, default is patch).
Or add no-release to skip.