feat: add footer with AI generation attribution to the main application layout.

src/client/src/App.tsx

@@ -89,6 +89,12 @@ export const App: React.FC = () => {
           {activeTab === 'tester' && <DeckTester />}
           {activeTab === 'bracket' && <TournamentManager />}
         </main>
+
+        <footer className="bg-slate-900 border-t border-slate-800 p-2 text-center text-xs text-slate-500 shrink-0">
+          <p>
+            Entire code generated by <span className="text-purple-400 font-medium">Antigravity</span> and <span className="text-sky-400 font-medium">Gemini Pro</span>
+          </p>
+        </footer>
       </div>
     </ToastProvider>
   );