feat: add custom brand colours to emails (#3005)

packages/email/preview/app/routes/$slug.tsx

@@ -0,0 +1,35 @@
+import { data } from 'react-router';
+
+import { EmailPlayground } from '../components/playground';
+import { getDefaultProps, getTemplate } from '../lib/templates';
+import type { Route } from './+types/$slug';
+
+export const loader = ({ params }: Route.LoaderArgs) => {
+  const { slug } = params;
+  const template = getTemplate(slug);
+
+  if (!template) {
+    throw data(`Unknown template: ${slug}`, { status: 404 });
+  }
+
+  return {
+    slug,
+    templateName: template.name,
+    fields: template.fields,
+    defaultProps: getDefaultProps(template.fields),
+  };
+};
+
+export const meta = ({ data: loaderData }: Route.MetaArgs) => {
+  if (!loaderData) {
+    return [{ title: 'Not found — Email Preview' }];
+  }
+
+  return [{ title: `${loaderData.templateName} — Email Preview` }];
+};
+
+const TemplatePage = ({ loaderData }: Route.ComponentProps) => {
+  return <EmailPlayground slug={loaderData.slug} fields={loaderData.fields} defaultProps={loaderData.defaultProps} />;
+};
+
+export default TemplatePage;