Nothing on this branch had ever executed on Windows. The unit tests pin the
gate's decision against a mocked taskkill, which cannot show that the decision
does anything to a real process: that `/T /F` reaps a detached grandchild, that
a refusal leaves that tree standing, or that the handle-addressed root kill the
refusal path falls back to reaps the root while orphaning descendants.
Adds a win32-gated live test covering all four, registered in both the
`package_windows` CI lane and `WINDOWS_PACKAGE_TESTS` as
`win32-test-lane-registration` requires.
Also completes the coverage doc's "never instrumented" list, which omitted the
macOS keyboard-input-source probe's POSIX group kill in `ipc/app.ts`.
Neil
24330104f4