feat: add NPC schedules with sleep, meal, and work periods

Add ACTION_SLEEP with home-position targeting and energy restoration. Embed schedule periods (SLEEP/MEAL/WORK/DISCRETIONARY) in ActionSelectionSystem with TimeOfDay from SimulationClock. NPCs sleep at night when energy is low, eat during meal periods when hungry, and work/discretionary the rest of the cycle. Home position stored per NPC and serialized through NPCStateRecord with backward-compatible fallback. Cycle duration persisted through save/restore. Includes headless test for sleep period, work period, meal hunger, energy restoration, serialization round-trip, and home targeting without world adapter.

simulation/SimNPC.gd

@@ -16,6 +16,7 @@ var intelligence: float
 var current_task: StringName = SimulationIds.ACTION_IDLE
 var task_state: StringName = TASK_STATE_IDLE
 var position: Vector3
+var home_position: Vector3
 
 var is_starving := false
 var starvation_ticks := 0
@@ -56,6 +57,7 @@ func _init(
 	position = Vector3(
 		random_source.randf_range(-8.0, 8.0), 0.0, random_source.randf_range(-8.0, 8.0)
 	)
+	home_position = position
 
 
 func die_from_starvation() -> void: