ci: run Windows unit tests on every PR

[peyton-alt]

https://entire.io/gh/entireio/cli/trails/956

Summary

• add a windows-latest unit-test job to the existing pull-request CI workflow
• run Windows/MSYS-named CLI tests with the Go version from go.mod
• wire the Windows job into the required aggregate test check

Why

Windows-only unit tests currently skip in every per-PR job because all required CI jobs run on Ubuntu. Go reports those skips as successful, so regressions in cmd.exe wrappers, PATHEXT discovery, plugin paths, and MSYS path handling are invisible until someone runs them manually on Windows.

This keeps the initial scope targeted: it reuses the existing Windows-focused tests without attempting to make every POSIX-oriented test harness Windows-compatible.

Closes #1843.

Validation

• mise run check
• mise run lint
• go test ./cmd/entire/cli/... -run (Windows|MSYS) -count=1 -v
• YAML parse validation and git diff --check

The real Windows-only test bodies will execute in the new windows-latest CI job.

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Note

Low Risk
CI workflow changes only; no runtime product or security-sensitive code paths are modified.

Overview
Adds a test-windows job on windows-latest that runs go test ./cmd/entire/cli/... with -run '(Windows|MSYS)', so Windows/MSYS-focused CLI tests actually execute on PRs instead of being skipped on Ubuntu.

The aggregate test job now depends on test-windows and fails the required check if that job does not succeed.

^{Reviewed by Cursor Bugbot for commit a1bfe9a. Configure here.}

[Copilot]

Pull request overview

Adds Windows coverage to the existing PR CI workflow by introducing a dedicated windows-latest unit-test job and gating the required aggregate test check on its success. This ensures Windows/MSYS-specific tests no longer silently skip on PRs.

Changes:

• Added a test-windows job on windows-latest that runs go test ./cmd/entire/cli/... -run '(Windows|MSYS)'.
• Wired the new Windows job into the required aggregate test job via needs and dependency assertions.