refactor: Update BuildCmdWrapper to use args splatting and add unit tests

[GordonBeeming]

This pull request improves the way command-line arguments are forwarded from Windows batch wrapper scripts to PowerShell functions, ensuring that quoted arguments are handled correctly. It also adds unit tests to verify the new behavior.

Improvements to command-line argument forwarding:

• Modified the BuildCmdWrapper method in ShellIntegration to use PowerShell's @args splatting and the -- separator when forwarding arguments, which preserves quoted arguments as single values.

Testing enhancements:

• Added new unit tests in ShellIntegrationTests.cs to verify that the wrapper script uses @args and the -- separator for both pwsh and Windows PowerShell.

Other changes:

• Removed the .worktrees/issue-65 subproject commit reference.

[Copilot]

Pull request overview

Refactors the Windows .cmd wrapper generation to forward arguments into PowerShell in a way that preserves quoting, and adds unit tests around the wrapper content to prevent regressions.

Changes:

• Update ShellIntegration.BuildCmdWrapper to forward args using PowerShell @args splatting (and a -- separator) instead of embedding %* inside the -Command string.
• Add unit tests validating the generated wrapper contains the new forwarding approach.
• Remove the .worktrees/issue-65 subproject commit reference file.

Reviewed changes

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

File	Description
app/Infrastructure/ShellIntegration.cs	Changes Windows CMD wrapper content to forward args via @args and --, and exposes the wrapper builder for unit tests.
tests/CopilotHere.UnitTests/ShellIntegrationTests.cs	Adds tests asserting the wrapper includes @args forwarding (and partially asserts -- %*).
.worktrees/issue-65	Removes an extraneous worktree/subproject commit reference.

[Copilot]

BuildCmdWrapper takes psPath but never uses it (the wrapper still hardcodes %USERPROFILE%\.copilot_here.ps1). Either remove the unused parameter (and adjust call sites/tests) or use psPath to build the script path in the generated CMD so the wrapper reflects the actual installed location.

[Copilot]

This change alters user-facing behavior (Windows CMD wrapper argument forwarding) but the repo’s versioning rule requires bumping the version consistently across all version locations so users re-download updates. Please increment the version in copilot_here.sh, copilot_here.ps1, Directory.Build.props, app/Infrastructure/BuildInfo.cs, and update the “Current version” in .github/copilot-instructions.md (see .github/copilot-instructions.md Script Versioning section).