frontend(error): add error page

src/app.css

@@ -18,4 +18,24 @@
 	html {
 		@apply bg-neutral-50 dark:bg-neutral-900;
 	}
+
+	/* Smooth theme transitions using View Transitions API */
+	::view-transition-old(root),
+	::view-transition-new(root) {
+		animation-duration: 0.3s;
+		animation-timing-function: ease-in-out;
+	}
+
+	/* Fallback transitions for browsers without View Transitions API */
+	@media (prefers-reduced-motion: no-preference) {
+		html {
+			transition: background-color 0.3s ease-in-out;
+		}
+
+		* {
+			transition: background-color 0.3s ease-in-out,
+			            border-color 0.3s ease-in-out,
+			            color 0.3s ease-in-out;
+		}
+	}
 }