chore: add documentation for svelte components

src/app/App.svelte

@@ -1,4 +1,14 @@
 <script lang="ts">
+/**
+ * App Component
+ *
+ * Application entry point component. Wraps the main page route within the shared
+ * layout shell. This is the root component mounted by the application.
+ *
+ * Structure:
+ * - Layout provides sidebar, header/footer, and page container
+ * - Page renders the current route content
+ */
 import Page from '$routes/Page.svelte';
 import Layout from './ui/Layout.svelte';
 </script>