Agent skill: add code-review skill for github copilot that can check for compliance with sundials style guide

[balos1]

No description provided.

[Copilot]

Pull request overview

Adds a new GitHub Copilot “code-review” skill intended to guide SUNDIALS PR reviews against the project’s developer-guide requirements.

Changes:

• Introduces a code-review skill checklist covering source-code and documentation compliance expectations.
• Defines a recommended review comment format for reporting developer-guide violations.

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[Steven-Roberts]

This looks reasonable to me. The "Source Review Checklist" and "Documentation Review Checklist" summarize conventions already in the developer docs, so it we update the docs, we'll need to remember to update this. I wonder if a review would differ much if we removed those sections. Copilot is already instructed to review our docs.

[balos1]

This looks reasonable to me. The "Source Review Checklist" and "Documentation Review Checklist" summarize conventions already in the developer docs, so it we update the docs, we'll need to remember to update this. I wonder if a review would differ much if we removed those sections. Copilot is already instructed to review our docs.

Yeah having the checklists enumerated may not be necessary. I am going to remove them.