Tests: Build-PSBuildUpdatableHelp #101
Description
Add Pester 5 integration tests for Build-PSBuildUpdatableHelp.
Scenarios to cover:
- Updatable help cabinet files are produced correctly
- Requires platyPS + MakeCab (Windows-only — skip test on Linux runners)
- Depends on shared fixture module (see Tests: Create shared fixture module #97
Parent issue: #17