新增原生工具调用数据结构与解析：SimpleAIClient.cs

AITool 增加 Schema 构造器与函数定义生成，所有工具补齐 GetParametersSchema()：AITool.cs 与 *.cs

Source/WulaFallenEmpire/EventSystem/AI/Tools/Tool_GetAvailablePrefabs.cs

@@ -13,6 +13,10 @@ namespace WulaFallenEmpire.EventSystem.AI.Tools
         public override string Description => "Returns a list of available building prefabs (blueprints) that can be summoned. " +
                                               "Use this to find the correct 'prefabDefName' for the 'call_prefab_airdrop' tool.";
         public override string UsageSchema => "{}";
+        public override Dictionary<string, object> GetParametersSchema()
+        {
+            return SchemaObject(new Dictionary<string, object>(), RequiredList());
+        }
 
         public override string Execute(string args)
         {