feat: enhance admin layout with navigation and return link; add name field for sign-up in login

src/routes/(admin)/admin/+layout.svelte

@@ -23,11 +23,11 @@
 
 <div class="flex min-h-screen bg-slate-900">
 	<!-- Sidebar -->
-	<aside class="w-64 border-r border-white/5 bg-slate-950">
+	<aside class="flex flex-col w-64 border-r border-white/5 bg-slate-950">
 		<div class="p-6">
 			<h2 class="text-lg font-black uppercase tracking-[0.15em] text-amber-50">Admin</h2>
 		</div>
-		<nav class="space-y-2 px-3">
+		<nav class="flex-1 space-y-2 px-3">
 			{#each navItems as item}
 				<a
 					href={item.href}
@@ -42,6 +42,16 @@
 				</a>
 			{/each}
 		</nav>
+		<div class="border-t border-white/5 p-3">
+			<a
+				href="/"
+				class="flex items-center gap-2 rounded-lg px-4 py-3 text-sm font-medium text-gray-300 transition-colors hover:bg-slate-800 hover:text-white"
+				title="Return to site"
+			>
+				<span>←</span>
+				<span>Retour au site</span>
+			</a>
+		</div>
 	</aside>
 
 	<!-- Main content -->