feat: add GSAP animations to signup, login, and dashboard pages; include Attachment serializer in backend

frontend/src/routes/signup/+page.svelte

@@ -4,6 +4,29 @@
 
 	export let data;
 	console.log(data);
+	import { gsap } from 'gsap'; // Import GSAP
+	import { onMount } from 'svelte';
+
+	onMount(() => {
+		gsap.from('.card', {
+			opacity: 0,
+			y: 50,
+			duration: 1,
+			ease: 'power3.out'
+		});
+		gsap.from('.text-center', {
+			opacity: 0,
+			x: -50,
+			duration: 1,
+			ease: 'power2.out'
+		});
+		gsap.from('.input', {
+			opacity: 0,
+			y: 30,
+			duration: 1,
+			ease: 'power2.out'
+		});
+	});
 
 	import FileImageBox from '~icons/mdi/file-image-box';