Convert CombatManager's phase state machine to coroutines so drawing,
interpreter-queue cards, and enemy actions each resolve one at a time
with visible delays, instead of an entire phase mutating state in a
single synchronous frame. Delays are skipped when UIPreferences.ReducedMotion
is set. Also drops the UI's old artificial cascade stagger for queued-card
animations since real per-card timing now provides the spacing.