refactor(settings): document benutzer non-null assertion in page.server.ts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/(app)/settings/+page.server.ts

@@ -15,6 +15,7 @@ export const load: PageServerLoad = async ({ fetch, locals }) => {
 	return {
 		stapleCount,
 		memberCount,
+		// hooks.server.ts guarantees benutzer is set for all (app) routes
 		userName: locals.benutzer!.name
 	};
 };