feat: define action completion costs

tests/npc_visual_lifecycle_test.gd

@@ -63,7 +63,8 @@ func _run() -> void:
 		SimulationIds.ACTION_GATHER_FOOD,
 		-1.0,
 		"Test shortage reason",
-		{SimulationIds.ACTION_GATHER_FOOD: 4.5}
+		{SimulationIds.ACTION_GATHER_FOOD: 4.5, SimulationIds.ACTION_PATROL: -1000000.0},
+		{SimulationIds.ACTION_PATROL: "Needs 1 Wood (0.5 available)"}
 	)
 	manager.latest_decisions[npc.id] = test_decision
 	manager.emit_signal("npc_decision_recorded", npc, test_decision)
@@ -75,6 +76,14 @@ func _run() -> void:
 		and npc.npc_name in inspector_label.text,
 		"NPC inspector should show the selected villager's real decision reason"
 	)
+	_check(
+		(
+			"Unavailable" in inspector_label.text
+			and "Patrol — Needs 1 Wood" in inspector_label.text
+			and "-1000000" not in inspector_label.text
+		),
+		"NPC inspector should explain rejected actions without sentinel utility scores"
+	)
 	var carried_food: MeshInstance3D = visual.get_node("CarriedFood")
 	_check(not carried_food.visible, "NPC should begin without a carried-food prop")
 	npc.add_inventory(SimulationIds.RESOURCE_FOOD, 1.0)