A Parc.RequestPreparer that uplifts allowed Ash shared-context keys into the
PARC context itself, then drops the raw :ash_context bundle that
AshParc.RequestBuilder placed in the request.
ResetAshContext SHOULD be declared the first preparer in a policy pipeline.
A policy decision must rest only on security-vetted context values. The raw Ash shared context is framework-internal and may be caller-influenced; by least privilege the decider receives only the allow-listed keys, so unvetted input cannot reach the decision.
Options:
:keys: the Ash shared-context keys to uplift; defaults to[](uplift nothing, just strip the bundle).