Allow approved prerelease publication

[ml6719]

What changed

• permits pending physical compatibility entries only when the triggering GitHub release is explicitly marked as a prerelease
• retains the hard physical-matrix gate for stable releases and manual workflow dispatches
• documents that prerelease packages are intended to provide the exact binaries for completing compatibility testing

Why

The owner explicitly approved publication of 0.6.0-preview.1 before the remaining Server 2012 R2/2016/2019/2022 and Windows 10/11 physical-host results are available. This keeps that exception narrow and preserves the stable-release safety gate.

Validation

• prerelease gate passes with an explicit pending-matrix warning
• stable gate remains blocked on all six pending operating systems
• Release build succeeded with zero warnings/errors
• 41/41 tests passed