feat: add sticky footer with branding

Add "Crumbs by Bretzel — made with 🥨 in Strasbourg" footer pinned
to the bottom of the page using flexbox layout.

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

src/routes/+layout.svelte

@@ -14,15 +14,19 @@
 	});
 </script>
 
-<div class="min-h-screen bg-white text-gray-900">
+<div class="flex min-h-screen flex-col bg-white text-gray-900">
 	<Header onMenuToggle={() => (sidebarOpen = !sidebarOpen)} />
 	<Sidebar open={sidebarOpen} />
 
-	<main class="pt-4 transition-all lg:ml-64">
+	<main class="flex-1 pt-4 transition-all lg:ml-64">
 		<div class="mx-auto max-w-7xl px-4">
 			{@render children()}
 		</div>
 	</main>
 
+	<footer class="pb-4 pt-8 text-center text-xs text-gray-400 lg:ml-64">
+		Crumbs by Bretzel &mdash; made with 🥨 in Strasbourg
+	</footer>
+
 	<Toast />
 </div>