feat: node info, build info and acrylic web theme

Squash of recent dev work: return_session login, backend switcher, line
detail timeline, overview strips, node platform/country/ISP info with flags
and icons, build info (version, tag, time) behind site.show_build, and the
acrylic display theme.

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）',
+  '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',
   'retention.metric_10s_hours': '10 秒精度的指标保留多少小时',