feat: add global scroll-to-top button with smooth animation

apps/web/src/app/layout.tsx

@@ -10,7 +10,7 @@ import { authConfig } from "@/lib/auth/config";
 import { SessionWrapper } from "./SessionWrapper";
 import { TRPCProvider } from "@/providers/trpc-provider";
 import { GeistSans } from "geist/font/sans";
-
+import ScrollToTop from "@/components/ui/ScrollToTop";
 // DM Mono - Used for code, terminal, and monospace text
 const dmMono = localFont({
   src: [
@@ -100,6 +100,7 @@ export const metadata: Metadata = {
   },
 };
 
+
 export default async function RootLayout({
   children,
 }: Readonly<{
@@ -126,6 +127,7 @@ export default async function RootLayout({
         </PostHogProvider>
         <Analytics />
         <SpeedInsights />
+        <ScrollToTop /> 
       </body>
     </html>
   );

apps/web/src/components/ui/ScrollToTop.tsx

@@ -0,0 +1,63 @@
+
+"use client";
+
+import { useState, useEffect } from "react";
+import { ChevronUp } from "lucide-react";
+import { cn } from "@/lib/utils";
+
+export default function ScrollToTop() {
+  const [isVisible, setIsVisible] = useState(false);
+
+  useEffect(() => {
+    const toggleVisibility = () => {
+      if (window.scrollY > 300) {
+        setIsVisible(true);
+      } else {
+        setIsVisible(false);
+      }
+    };
+
+    window.addEventListener("scroll", toggleVisibility);
+    toggleVisibility();
+    return () => {
+      window.removeEventListener("scroll", toggleVisibility);
+    };
+  }, []);
+
+
+  const scrollToTop = () => {
+    window.scrollTo({
+      top: 0,
+      behavior: "smooth",
+    });
+  };
+
+  return (
+    <>
+      {/* Button only renders when isVisible is true */}
+      {isVisible && (
+        <button
+          onClick={scrollToTop}
+          className={cn(
+            "fixed bottom-8 right-8 z-50",
+            "group",
+            "w-12 h-12 rounded-[16px]",
+            "shadow-lg hover:shadow-xl hover:shadow-brand-purple/20",
+            "transition-all duration-300 ease-in-out",
+            "animate-in fade-in slide-in-from-bottom-4",
+            "cursor-pointer",
+            "active:scale-95",
+            "bg-surface-elevated border-2 border-border-subtle",
+            "hover:border-brand-purple hover:bg-surface-elevated-hover",
+            "focus:outline-none focus:ring-2 focus:ring-brand-purple focus:ring-offset-2 focus:ring-offset-surface-root"
+          )}
+          aria-label="Scroll to top"
+        >
+          <ChevronUp 
+            className="w-6 h-6 text-brand-purple mx-auto transition-transform group-hover:translate-y-[-2px]" 
+          />
+        </button>
+      )}
+    </>
+  );
+}