feat: choose which probes link to which agents from the admin

The panel decides the probe/agent pairs and probes always dial out. A new
fleet.auto_link setting connects every probe to every agent (default); with it
off only the pairs chosen by hand connect, and any pair can be forced on or
off. The Probes page has a link matrix with the switch and per-pair toggles.

web/shared/i18n.ts

@@ -143,6 +143,7 @@ export function translateCode(code: string): string | undefined {
 
 const SETTINGS: Record<string, string> = {
   'site.public': '匿名访客能不能读展示页的数据（关闭时只有登录的管理员能看）',
+  'fleet.auto_link': '所有 Probe 自动连接所有 Agent（关闭后只连在「Probe → 线路」里手动选中的）',
   'site.show_build': '展示页底部和节点卡片上显示后端、前端、Agent、Probe 的版本、tag 和构建时间',
   'retention.raw_days': '持续任务的原始数据块保留多少天',
   'retention.test_raw_days': '按需测试的原始数据块保留多少天',