feat(nextly): resolve an entry preview url in one place

.changeset/preview-url-resolver.md

@@ -0,0 +1,32 @@
+---
+"nextly": patch
+"create-nextly-app": patch
+"@nextlyhq/admin": patch
+"@nextlyhq/admin-css": patch
+"@nextlyhq/blocks-engine": patch
+"@nextlyhq/blocks-react": patch
+"@nextlyhq/ui": patch
+"@nextlyhq/adapter-drizzle": patch
+"@nextlyhq/adapter-postgres": patch
+"@nextlyhq/adapter-mysql": patch
+"@nextlyhq/adapter-sqlite": patch
+"@nextlyhq/storage-s3": patch
+"@nextlyhq/storage-uploadthing": patch
+"@nextlyhq/storage-vercel-blob": patch
+"@nextlyhq/plugin-form-builder": patch
+"@nextlyhq/plugin-page-builder": patch
+"@nextlyhq/plugin-seo": patch
+"@nextlyhq/plugin-sdk": patch
+"@nextlyhq/eslint-config": patch
+"@nextlyhq/prettier-config": patch
+"@nextlyhq/telemetry": patch
+"@nextlyhq/tsconfig": patch
+"@nextlyhq/builder": patch
+"@nextlyhq/module-specifiers": patch
+---
+
+Resolve an entry preview URL in one place, on the server.
+
+A collection declares its preview two ways and they are disjoint: code-first writes a function of the entry, a UI-created collection writes a template string. Both are now answered by one resolver, so the admin asks where an entry previews instead of deciding for itself.
+
+Resolving on the server is what makes the preview button reachable for editors and authors. The site URL sits behind a settings permission neither role holds, so a browser-side answer was unavailable to exactly the people who share previews.