feat(core): 优化扩展启动逻辑并修复类型提示问题

- 修改 CoreService 启动逻辑，将 system 扩展实例存入 bootedExtensionMap
- 修复 functions.php 中 running_in_console 函数返回值缺失问题
- 统一多个服务类中的可空参数类型声明
- 新增 HelloCron 定时任务并注册到扩展中
- 优化 GatheringCrontabEventHook 中定时任务初始化逻辑
- 增强 Cron 注解解析与任务执行检查机制

src/Config.php

@@ -28,7 +28,7 @@ class Config
         getConfig as traitGetConfig;
     }
 
-    public function getConfig(string $key = null, mixed $default = null): mixed
+    public function getConfig(?string $key = null, mixed $default = null): mixed
     {
         if ($key == 'merchant_no') {
             return $this->getConfig('sub_merchant_list')[0]['merchant_no'];

src/Service/TransactionService.php

@@ -64,7 +64,7 @@ class TransactionService
         string             $payOrderNo = '',
         string             $settleType = '',
         string             $remark = '',
-        TradeAccBusiFields $accBusiFields = null,
+        ?TradeAccBusiFields $accBusiFields = null,
     ): object
     {
         $request = new TransPreorderRequest();