feat(core-shared): add payload barrel export

packages/core-shared/src/payload/index.ts

@@ -0,0 +1,6 @@
+export { isAdmin } from "./access/is-admin";
+export { slugField } from "./fields/slug-field";
+export { seoFields } from "./fields/seo-fields";
+export { cta } from "./blocks/cta";
+export { setPublishedAt } from "./hooks/set-published-at";
+export { slugifyIfMissing } from "./hooks/slugify-if-missing";