feat: implement loading indicators in transactions page and loading component for improved user feedback during data fetching

app/transactions/loading.tsx

@@ -1,3 +1,11 @@
+import { RefreshCw } from "lucide-react";
+
 export default function Loading() {
-  return null;
+  return (
+    <div className="flex h-screen bg-background">
+      <main className="flex-1 flex items-center justify-center">
+        <RefreshCw className="w-8 h-8 animate-spin text-muted-foreground" />
+      </main>
+    </div>
+  );
 }