chore: add minimal Gemini Code Assist configuration and update CODEOWNERS

[nearlyforget]

Description

This PR introduces a minimal configuration for Gemini Code Assist by adding .gemini/config.yaml and ensures the new configuration directory is properly owned in CODEOWNERS.

Category (Required)

Please select one or more categories that apply to this change.

• Core Protocol: Changes to the base communication layer, global context, or breaking refactors. (Requires Technical Council approval)
• Governance/Contributing: Updates to GOVERNANCE.md, CONTRIBUTING.md, or CODEOWNERS. (Requires Governance Council approval)
• Capability: New schemas (Discovery, Cart, etc.) or extensions. (Requires Maintainer approval)
• Documentation: Updates to README, or documentations regarding schema or capabilities. (Requires Maintainer approval)
• Infrastructure: CI/CD, Linters, or build scripts. (Requires DevOps Maintainer approval)
• Maintenance: Version bumps, lockfile updates, or minor bug fixes. (Requires DevOps Maintainer approval)
• SDK: Language-specific SDK updates and releases. (Requires DevOps Maintainer approval)
• Samples / Conformance: Maintaining samples and the conformance suite. (Requires Maintainer approval)
• UCP Schema: Changes to the ucp-schema tool (resolver, linter, validator). (Requires Maintainer approval)
• Community Health (.github): Updates to templates, workflows, or org-level configs. (Requires DevOps Maintainer approval)

Related Issues

Checklist

• I have followed the Contributing Guide.
• I have updated the documentation (if applicable).
• My changes pass all local linting and formatting checks.
• (For Core/Capability) I have included/updated the relevant JSON schemas.
• I have regenerated Python Pydantic models by running generate_models.sh under python_sdk.

Screenshots / Logs (if applicable)

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[gemini-code-assist]

Code Review

This pull request updates the .github/CODEOWNERS file to include the /.gemini/ directory. Feedback was provided to sort the entries alphabetically for better maintainability and to correct alignment inconsistencies.

[gemini-code-assist]

For improved readability and long-term maintainability, it's a good practice to keep entries in the CODEOWNERS file sorted alphabetically within their respective sections. This also provides an opportunity to fix a minor alignment inconsistency in this block.

/.gemini/                 @Universal-Commerce-Protocol/devops-maintainers @Universal-Commerce-Protocol/maintainers @Universal-Commerce-Protocol/tech-council @Universal-Commerce-Protocol/governance-council
/.pre-commit-config.yaml @Universal-Commerce-Protocol/devops-maintainers @Universal-Commerce-Protocol/maintainers @Universal-Commerce-Protocol/tech-council @Universal-Commerce-Protocol/governance-council
/pyproject.toml           @Universal-Commerce-Protocol/devops-maintainers @Universal-Commerce-Protocol/maintainers @Universal-Commerce-Protocol/tech-council @Universal-Commerce-Protocol/governance-council
/uv.lock                  @Universal-Commerce-Protocol/devops-maintainers @Universal-Commerce-Protocol/maintainers @Universal-Commerce-Protocol/tech-council @Universal-Commerce-Protocol/governance-council