style: limit transaction detail dialog width to match wallet UI

Add max-w-md constraint to transaction detail dialog to match
the width of the balance display and send/receive buttons.
This creates a consistent, compact layout throughout the wallet UI.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/WalletViewer.tsx

@@ -1288,7 +1288,7 @@ export default function WalletViewer() {
           }
         }}
       >
-        <DialogContent className="max-h-[70vh] flex flex-col">
+        <DialogContent className="max-w-md max-h-[70vh] flex flex-col">
           <DialogHeader>
             <DialogTitle>Transaction Details</DialogTitle>
           </DialogHeader>