Update copilot instructions with comprehensive guidance for shallow clone environment

[Copilot]

Enhanced the .github/copilot-instructions.md file to provide comprehensive guidance specifically tailored for the GitHub Copilot Coding Agent working in a shallow clone environment.

Key Improvements

Environment Setup Clarification: Added a dedicated section explaining why NBGV_GitEngine=Disabled is required when working with Nerdbank.GitVersioning in shallow clone environments. The GitHub Copilot Coding Agent operates on shallow clones by default, which breaks version calculation that depends on git history.

Step-by-Step Build Instructions: Expanded the build guidance with specific commands and workflow:

• Initial setup with ./init.ps1 or pwsh ./init.ps1
• Building with ./build.ps1 or pwsh ./build.ps1
• Testing with dotnet test --filter "TestCategory!=FailsInCloudTest"

Enhanced Testing Guidelines: Provided clearer guidance on running tests, including the rationale for filtering out unstable tests that fail in cloud environments, and emphasized the importance of comprehensive test coverage.

Improved Structure and Organization: Reorganized content into logical sections with clear headers and better flow, making it easier for the Copilot agent to find relevant information quickly.

Coding Standards Enhancement: Expanded the coding style section with additional guidance on following existing patterns, meaningful naming conventions, and comprehensive documentation requirements.

These changes ensure that the Copilot Coding Agent has all the necessary information to work effectively with this repository, avoiding common pitfalls related to shallow clones and providing clear guidance for building, testing, and maintaining code quality standards.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• aka.ms
  • Triggering command: curl -I -sSL --retry 5 --retry-delay 2 --connect-timeout 15 REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[AArnott]

I wonder... is this true? Does that defeat any of the tests? We certainly don't regularly test with such an environment variable set.