fix: enforce village resource invariants

tests/action_system_boundaries_test.gd

@@ -68,6 +68,20 @@ func _test_selection_and_execution_are_separate() -> void:
 		work_selection.scores.size() == 4,
 		"Ordinary work selection should expose all compared utility scores"
 	)
+	var guard := SimNPC.new(701, "BoundaryGuard", SimulationIds.PROFESSION_GUARD, 5.0, 5.0)
+	guard.hunger = 20.0
+	guard.energy = 80.0
+	village.food = 100.0
+	village.wood = 0.0
+	village.safety = 0.0
+	village.knowledge = 100.0
+	village.update_modifiers()
+	village.update_priorities()
+	var unfunded_selection := selector.select_action(guard, village, 0.5)
+	_check(
+		unfunded_selection.action_id == SimulationIds.ACTION_GATHER_WOOD,
+		"A guard should gather wood instead of selecting patrol when its material cost is unavailable"
+	)
 
 
 func _test_target_resolution_and_travel_are_separate() -> void: