fix(qr-button): match height of stacked buttons

- Change from width-based to height-based sizing (height: 100%)
- Button now takes full height of parent container
- Increase QR code from 52px to 72px to fill larger button
- Button remains square with aspectRatio: 1

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/components/common/QRCodeButton.tsx

@@ -37,9 +37,8 @@ export function QRCodeButton({ url, style }: QRCodeButtonProps) {
     padding: '4px',
     fontSize: '16px',
     color: 'rgba(253, 186, 116, 1)',
-    width: '100%',
+    height: '100%',
     aspectRatio: '1',
-    alignSelf: 'stretch',
     flexShrink: 0,
     ...style,
   }
@@ -62,7 +61,7 @@ export function QRCodeButton({ url, style }: QRCodeButtonProps) {
             Object.assign(e.currentTarget.style, buttonStyles)
           }}
         >
-          <QRCodeSVG value={url} size={52} level="L" />
+          <QRCodeSVG value={url} size={72} level="L" />
         </button>
       </Popover.Trigger>