Auto-exclude copilot environment from CI/CD deployments

[aholstrup1]

When the GitHub Copilot coding agent is enabled on a repository, GitHub auto-creates an environment named copilot. DetermineDeploymentEnvironments enumerates all GitHub environments and was picking it up as a CD target, so the Deploy job ran with no DeployTo settings and no AuthContext secret and failed with Authentication failed at Deploy.ps1:128.

This treats copilot the same way github-pages is already treated: it is appended to the implicit excludeEnvironments list, so it never reaches the deployment matrix.

Changes:

• Actions/DetermineDeploymentEnvironments/DetermineDeploymentEnvironments.ps1 - add copilot next to github-pages in the implicit exclude list
• Scenarios/settings.md - mention copilot in the existing excludeEnvironments description
• RELEASENOTES.md - note the fix under Issues

Fixes: #2277

[Copilot]

Pull request overview

This PR prevents GitHub’s auto-created copilot environment (created when the Copilot coding agent is enabled) from being treated as a CI/CD deployment target by DetermineDeploymentEnvironments, avoiding Deploy job failures due to missing DeployTo* settings / auth context.

Changes:

• Implicitly appends copilot to the excludeEnvironments list (alongside github-pages) in DetermineDeploymentEnvironments.
• Documents the implicit exclusion of copilot in Scenarios/settings.md.
• Adds a release note entry describing the fix for Issue #2277.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
Actions/DetermineDeploymentEnvironments/DetermineDeploymentEnvironments.ps1	Excludes copilot from the environment enumeration used to build the deployment matrix.
Scenarios/settings.md	Updates settings documentation to note that copilot is implicitly excluded.
RELEASENOTES.md	Records the fix in the release notes.