feat: 导出单插件重载到 SDK (CORE_PLUGIN_RELOAD_ONE/48 + LIST/49 + IS_DISABLED/50)

- PluginManager 接口新增 ReloadOne(name) error
- cabi dispatch: case 48 单插件重载, 49 列已加载, 50 查询禁用
- 外部 SDK 新增 PluginMgrAPI(ReloadOne/ListLoadedPlugins/IsPluginDisabled)  + bridge dispatchPluginMgr 注入

internal/meta/meta.go

@@ -101,4 +101,7 @@ const (
 	CoreSettingsPlugins     = 45
 	CoreRegisterInputCh     = 46
 	CoreInjectInputSync     = 47
+	CorePluginReloadOne     = 48
+	CorePluginListLoaded    = 49
+	CorePluginIsDisabled    = 50
 )