feat: add Expo QR code generation and modal for mobile preview

Introduce Expo QR code functionality to allow users to preview their projects on mobile devices. Added a new QR code modal component, integrated it into the chat and preview components, and implemented Expo URL detection in the shell process. This enhances the mobile development workflow by providing a seamless way to test Expo projects directly on devices.

- Clean up and consolidate Preview icon buttons while removing redundant ones.

app/components/ui/Dialog.tsx

@@ -116,7 +116,7 @@ export const Dialog = memo(({ children, className, showCloseButton = true, onClo
       <RadixDialog.Content asChild>
         <motion.div
           className={classNames(
-            'fixed top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 bg-white dark:bg-gray-950 rounded-lg shadow-xl border border-bolt-elements-borderColor z-[9999] w-[520px]',
+            'fixed top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 bg-white dark:bg-gray-950 rounded-lg shadow-xl border border-bolt-elements-borderColor z-[9999] w-[520px] focus:outline-none',
             className,
           )}
           initial="closed"