chore: use literal shells for the Windows installer CI matrix [skip changelog]
The Windows installer smoke-test job set shell from a matrix expression, which GitHub Actions rejects as an invalid workflow file, so the Test workflow no longer parses on main. The job now has one conditional step per matrix entry with a literal shell, so both powershell and pwsh still run as separate matrix jobs.
Summary by cubic
Fixes the Windows installer smoke-test job so the Test workflow parses on main. GitHub Actions rejects shell values from matrix expressions, so the job now uses one conditional step per matrix entry with a literal shell, keeping powershell and pwsh as separate matrix jobs. The test script also loads the Archive module before replacing Expand-Archive and captures installer output as it streams, initializing it before the test body, so test failures print the output.