Time effect facade + backend behaviour. Nodes call Bloccs.Effects.Time.now/1
against ctx.effects.time. Default backend is the real wall clock
(Time.System); tests can bind a frozen-clock backend.
Summary
Types
@type cap() :: struct()
Callbacks
@callback now(cap()) :: DateTime.t()
Functions
@spec now(cap()) :: DateTime.t()
Current time through the bound clock backend.