ui: Web3 shop rename, merchant info header, shopping cart with floating button and two-column checkout

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/Decentralized/Session.cs

@@ -120,6 +120,7 @@ namespace Decentralized
         {
             Data = null;
             WalletWindow.Reset();
+            TerminalWindow.ClearCart();
             try
             {
                 string json = ModHelper.GetModData(ModInfo.Id, Key);