added backdrop and loading screen

app/components/ui/LoadingOverlay.tsx

@@ -0,0 +1,14 @@
+export const LoadingOverlay = ({ message = 'Loading...' }) => {
+  return (
+    <div className="fixed inset-0 flex items-center justify-center bg-black/80 z-50 backdrop-blur-sm">
+      {/* Loading content */}
+      <div className="relative flex flex-col items-center gap-4 p-8 rounded-lg bg-bolt-elements-background-depth-2 shadow-lg">
+        <div
+          className={'i-svg-spinners:90-ring-with-bg text-bolt-elements-loader-progress'}
+          style={{ fontSize: '2rem' }}
+        ></div>
+        <p className="text-lg text-bolt-elements-textTertiary">{message}</p>
+      </div>
+    </div>
+  );
+};