* test(ephemeral-vm): make VM runtime store suites pass on Windows
Drop the process.platform=linux stubs (they made secure writes fsync a
read-only handle, EPERM on Windows, and spawned recipes POSIX-style) and
remove temp dirs through one allSettled removeTree helper so Windows ACL
work cannot fail teardown with EBUSY.
* test: restore the rmSync import dropped by the merge from main
