Dispatch-time logic for DoubleDown.Double's canonical handler.
This module contains the runtime dispatch functions that execute
inside NimbleOwnership.get_and_update when a contract operation
is called. It reads expects, per-op fakes, per-op stubs, and
fallback config from CanonicalHandlerState at dispatch time.
Separated from DoubleDown.Double (setup-time API) for clarity —
setup code is called by tests, dispatch code runs inside the
NimbleOwnership GenServer.
Dispatch priority
rejects > expects > per-op fakes > per-op stubs > fallback > raise