fix(web): remove ephemeral sandbox count from Box status display

The active_sessions count reflects transient sandbox containers that
expire after 5 minutes of inactivity, making it misleading in the UI.
Keep only connection status, backend, profile, and error count.

web/src/i18n/locales/zh-Hans.ts

@@ -452,7 +452,6 @@ const zhHans = {
     boxUnavailable: '不可用',
     boxBackend: '后端',
     boxProfile: '配置',
-    boxSessions: '会话数',
     boxErrors: '错误数',
     boxStatusLoadFailed: '加载 Box 状态失败',
     failedToGetDebugInfo: '获取调试信息失败',