feat: guard to prevent premature form submissions while uploading

assets/styles/components/button.css

@@ -1,6 +1,6 @@
 .btn {
     @apply inline-flex space-x-1 justify-center rounded-lg text-sm uppercase font-semibold py-2.5 px-4;
-    @apply bg-primary text-white hover:bg-primary/80 shadow-md;
+    @apply bg-primary text-white hover:bg-primary/80 shadow-md disabled:opacity-50 disabled:cursor-not-allowed;
 }
 
 .btn--small {