fix(nav): rename tab from 'Geteilte Listen' to 'Listen'

frontend/src/App.tsx

@@ -505,7 +505,7 @@ export const App: React.FC = () => {
               className={`tab-btn ${activeTab === 'lists' ? 'tab-btn-active' : ''}`}
             >
               <ShoppingCart className="w-4 h-4" />
-              <span>Geteilte Listen</span>
+              <span>Listen</span>
             </button>
           </div>