semantic update

frontend/src/routes/+layout.svelte

@@ -14,6 +14,14 @@
 -->
 
 <!-- [DEF:layout:Module] -->
+<!--
+@TIER: STANDARD
+@SEMANTICS: app-layout, auth-gating, navigation-shell
+@PURPOSE: Bind global layout shell and conditional login/full-app rendering.
+@LAYER: UI
+@RELATION: BINDS_TO -> frontend.src.lib.components.layout.Sidebar
+@INVARIANT: Login route bypasses shell; all other routes are wrapped by ProtectedRoute.
+-->
 <script>
     import '../app.css';
     import Navbar from '../components/Navbar.svelte';