refactor(templates): apply activeClass helper and full-width layout

- Replace inline ternary operators with activeClass helper function
- Change layout containers from max-w-7xl to w-full for full-width design
- Update file path references in error messages for better debugging

templates/admin_sidebar.templ

@@ -5,25 +5,16 @@ templ AdminSidebar(user User, currentPath string) {
 		<div class="p-6">
 			<h2 class="text-lg font-semibold mb-6" style="color: var(--text-primary)">Admin Panel</h2>
 			<nav class="space-y-2">
-				<a href="/admin"
-				   class={"block px-4 py-2 rounded-lg " +
-					   ("bg-accent text-bg-primary" if currentPath == "/admin" else "hover:opacity-80")}
-				   style="color: var(--text-primary)">
+				<a href="/admin" class={activeClass(currentPath, "/admin")} style="color: var(--text-primary)">
 					🏠 Dashboard
 				</a>
-				<a href="/admin/users"
-				   class={"block px-4 py-2 rounded-lg " +
-					   ("bg-accent text-bg-primary" if currentPath == "/admin/users" else "hover:opacity-80")}
-				   style="color: var(--text-primary)">
+				<a href="/admin/users" class={activeClass(currentPath, "/admin/users")} style="color: var(--text-primary)">
 					👤 User Administration
 				</a>
-				<a href="/admin/library"
-				   class={"block px-4 py-2 rounded-lg " +
-					   ("bg-accent text-bg-primary" if currentPath == "/admin/library" else "hover:opacity-80")}
-				   style="color: var(--text-primary)">
+				<a href="/admin/library" class={activeClass(currentPath, "/admin/library")} style="color: var(--text-primary)">
 					📚 Library Management
 				</a>
 			</nav>
 		</div>
 	</aside>
-}
+}