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/en-US.ts

@@ -66,7 +66,7 @@ const enUS = {
     and: 'and',
     dataCollectionPolicy: 'Data Collection Policy',
     dataCollectionPolicyUrl:
-      'https://docs.langbot.app/en/insight/data-collection-policy',
+      'https://link.langbot.app/en/docs/data-policy',
     loading: 'Loading...',
     fieldRequired: 'This field is required',
     or: 'or',