Update version number in CSharpExpert agent

[jlbeard84]

In order to better determine if a given agent file in a repository is out of date, shouldn't the version # be incremented when changes are made? I see that this one is stale and as such I missed updating the version of it I have in my repositories.

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• My contribution adds a new instruction, prompt, or chat mode file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, or chat mode with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.

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Description

Updating the date of the agent on the C# Expert Agent, as I would imagine that is a trigger for people to update the copy in their local repositories.

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Type of Contribution

• New instruction file.
• New prompt file.
• New chat mode file.
• New collection file.
• New skill file.
• Update to existing instruction, prompt, chat mode, collection or skill.
• Other (please specify):

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Additional Notes

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[Copilot]

Pull request overview

This pull request updates the version comment in the CSharpExpert agent file to reflect the current date, helping users identify when the agent was last updated.

Changes:

• Updated version comment from 2025-10-27a to 2026-01-20a in the CSharpExpert agent file