feat(timer): 新增定时器配置、日志和主机的后台管理界面

T10: TimerConfig CURD - task management with run_type/status editing,
     manual trigger button, task_name read-only, no add/delete
T11: TimerLog CURD - read-only log viewer with filters and color badges
T12: Host list enhanced - is_master column, setMaster button

extend/base/admin/controller/system/HostBase.php

@@ -20,5 +20,26 @@ class HostBase extends AdminController
         $this->model = new \app\admin\model\SystemHost();
 
         $this->assign('select_list_status', $this->model::SELECT_LIST_STATUS, true);
+        $this->assign('select_list_is_master', $this->model::SELECT_LIST_IS_MASTER, true);
+    }
+
+    /**
+     * 设置主节点.
+     *
+     * @auth true
+     */
+    public function setMaster()
+    {
+        $nodeId = $this->request->param('node_id', '');
+        if (empty($nodeId)) {
+            $this->error('参数错误');
+        }
+
+        $result = \app\common\service\HostService::setMasterNode($nodeId);
+        if ($result) {
+            $this->success('主节点切换成功');
+        } else {
+            $this->error('节点不存在');
+        }
     }
 }