refactor: replace docs.langbot.app URLs with link.langbot.app short links

All documentation URLs now go through Cloudflare Bulk Redirects
(link.langbot.app) so future doc path changes won't break
already-released versions.

Short link format: link.langbot.app/{lang}/docs/{topic}
Supported languages: zh, en, ja

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

@@ -65,7 +65,7 @@ const zhHans = {
     and: '和',
     dataCollectionPolicy: '数据收集政策',
     dataCollectionPolicyUrl:
-      'https://docs.langbot.app/zh/insight/data-collection-policy',
+      'https://link.langbot.app/zh/docs/data-policy',
     loading: '加载中...',
     fieldRequired: '此字段为必填项',
     or: '或',