feat(timer): 新增配置同步到数据库及主节点选举

T5: TimerServiceBase.syncConfigToDatabase() - syncs task config to DB
T6: HostServiceBase - auto master election, stale node detection,
    getMasterNode/setMasterNode methods

extend/base/common/service/HostServiceBase.php

@@ -75,6 +75,23 @@ class HostServiceBase
             }
 
             $host->save($data);
+
+            // 主节点自动选举：若无在线主节点，当前节点自动成为主节点
+            $master = SystemHost::where('is_master', 1)->where('status', 1)->find();
+            if (empty($master)) {
+                $host->is_master = 1;
+                $host->save();
+                Log::info("节点 [{$nodeId}] 自动当选为主节点。");
+            }
+
+            // 过期节点检测：超过90秒无心跳的节点标记为离线
+            $staleTime = date('Y-m-d H:i:s', time() - 90);
+            $staleCount = SystemHost::where('status', 1)
+                ->where('last_heartbeat_at', '<', $staleTime)
+                ->update(['status' => 0]);
+            if ($staleCount > 0) {
+                Log::info("已将 {$staleCount} 个过期节点标记为离线。");
+            }
         } catch (\Exception $e) {
             throw $e;
             Log::error("节点 [{$nodeId}] 心跳更新失败: " . $e->getMessage());
@@ -110,4 +127,38 @@ class HostServiceBase
             'php_version' => PHP_VERSION,
         ];
     }
+
+    /**
+     * 获取当前主节点的node_id.
+     *
+     * @return string|null 返回主节点ID，无主节点时返回null
+     */
+    public static function getMasterNode(): ?string
+    {
+        $master = SystemHost::where('is_master', 1)->where('status', 1)->find();
+        return $master ? $master->node_id : null;
+    }
+
+    /**
+     * 手动切换主节点.
+     *
+     * @param string $nodeId 目标节点的node_id
+     * @return bool 切换成功返回true，节点不存在返回false
+     */
+    public static function setMasterNode(string $nodeId): bool
+    {
+        // 先清除所有主节点标记
+        SystemHost::where('is_master', 1)->update(['is_master' => 0]);
+
+        // 设置新主节点
+        $host = SystemHost::where('node_id', $nodeId)->find();
+        if ($host) {
+            $host->is_master = 1;
+            $host->save();
+
+            return true;
+        }
+
+        return false;
+    }
 }