move better-auth demo to auth dir

src/routes/auth/+page.server.ts

@@ -0,0 +1,20 @@
+import { redirect } from '@sveltejs/kit';
+import type { Actions } from './$types';
+import type { PageServerLoad } from './$types';
+import { auth } from '$lib/server/auth';
+
+export const load: PageServerLoad = (event) => {
+  if (!event.locals.user) {
+    return redirect(302, '/auth/login');
+  }
+  return { user: event.locals.user };
+};
+
+export const actions: Actions = {
+  signOut: async (event) => {
+    await auth.api.signOut({
+      headers: event.request.headers
+    });
+    return redirect(302, '/auth/login');
+  }
+};