refactor: unify animal content packs

simulation/animals/AnimalCatalog.gd

@@ -1,8 +1,6 @@
 class_name AnimalCatalog
 extends Resource
 
-const CORE_CATALOG_PATH := "res://simulation/animals/definitions/core_animals.tres"
-
 @export var animals: Array[AnimalDefinition] = []
 
 var _definitions_by_id: Dictionary = {}
@@ -11,10 +9,12 @@ var _errors: Array[String] = []
 
 
 static func create_core() -> AnimalCatalog:
-	var catalog := load(CORE_CATALOG_PATH) as AnimalCatalog
-	if catalog != null:
-		catalog.rebuild()
-	return catalog
+	var content := ContentCatalog.create_core()
+	if content == null or not content.is_valid():
+		return null
+	var catalog := AnimalCatalog.new()
+	catalog.animals = content.get_animals()
+	return catalog if catalog.rebuild().is_empty() else null
 
 
 func rebuild() -> Array[String]: