feat: add CASPOS Store brand and Demo badge to admin sidebar footer

shop/app/admin/layout.tsx

@@ -63,11 +63,17 @@ export default async function AdminLayout({
           </Link>
         </nav>
 
-        <div className="p-4 border-t border-white/5">
+        <div className="p-4 border-t border-white/5 space-y-4">
           <button className="flex w-full items-center gap-3 px-3 py-2 rounded-lg text-slate-400 hover:text-white hover:bg-white/5 transition-all">
             <LogOut className="w-5 h-5" />
             Abmelden
           </button>
+          <div className="px-3 pt-2 flex items-center gap-2 border-t border-white/5 opacity-60">
+            <span className="font-bold text-sm tracking-tighter text-white">CASPOS Store</span>
+            <span className="text-[10px] bg-amber-500/20 text-amber-400 px-2 py-0.5 rounded-full font-semibold uppercase tracking-wider border border-amber-500/30">
+              Demo
+            </span>
+          </div>
         </div>
       </aside>