Expand description
Effect dispatcher — translate an Effect<'i, Authorized> into
StepStage deltas.
Inputs: an authorized Effect (Op + originating principal + branded
instance), the running StepStage, current Tick, and the kernel’s
next_scheduled_id counter.
Output: side-effect on StepStage only — no Instance mutation here;
runtime::apply::apply_stage commits the stage post-dispatch.