ci: restore windows unit tests

[code-JDS]

Issue for this PR

Closes #272

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Restores Windows unit coverage in .github/workflows/test.yml without pulling in the upstream Blacksmith-based test workflow.

This PR adds GitHub Hosted windows-2022 jobs for the existing app and opencode unit checks, keeps the current Linux jobs unchanged, and uses actions/setup-node@v4 with Node 24 before the shared Bun setup to match the Windows CI stability fix used upstream.

After the first Windows CI run exposed opencode-specific failures, this branch also adds a follow-up Windows-only fix:

• tighten Windows cross-drive path checks in Filesystem.contains() and Filesystem.overlaps()
• skip a WSL-only resolveInput() test on native Windows
• harden legacy SQLite DB copying on Windows with retry-on-lock behavior
• deflake the LegacyDB cleanup test logic for Windows WAL/SHM handle release

It also updates docs/ci-guide.md so the workflow documentation matches the restored Windows coverage and no longer claims that Windows unit tests are excluded because of the old checkout-time path-length issue.

How did you verify your code works?

• Ran bun test:unit in packages/app successfully
• Ran bun test src/tool/path.test.ts in packages/opencode
• Ran bun test test/file/path-traversal.test.ts in packages/opencode
• Ran bun test test/storage/legacy-db.test.ts in packages/opencode
• Pre-push bun turbo typecheck completed successfully
• Ran git diff --check

Screenshots / recordings

Not applicable.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR