Ensure the GroomingToken mechanism indeed creates an
exclusive section protected against concurrent corruption:
Use a without / with-protection test and verify
the results are exact vs. grossly broken
T thread holding the »Grooming Token" is permitted to
manipulate scheduler internals and thus also to define new
activities; this logic is implemented as an Atomic lock,
based on the current thread's ID.
Notably both Layers are conceived as functionality providers;
only at Scheduler top-Level will functionality be combined with
external dependencies to create the actual service.
