feat: desktop banner peek with framer-motion blur

Match Figma node 4366-11092 desktop banner design:
- Slides shrink to 78%/72%/60% width on md/lg/xl with snap-center,
  first/last get matching left/right margin so the edges still center.
- Each slide is wrapped in a framer-motion m.div that animates filter,
  opacity, and scale between active and idle states.
- goTo and scroll/drag handlers use the slide's real offsetWidth so
  centering math holds at every breakpoint; mobile (full-width, snap-start
  visual) is unchanged.

src/components/FigmaBanner.tsx

@@ -6,8 +6,10 @@ import {
   type MouseEvent as ReactMouseEvent,
   type PointerEvent as ReactPointerEvent,
 } from "react";
+import { m } from "framer-motion";
 import { useNavigate } from "react-router-dom";
 import { assetUrl, getJSON, itemsOrEmpty, readJSONCache } from "../api";
+import { EASE_OUT } from "../motion";
 import { langQuery, useI18n, type Lang } from "../i18n";
 
 const FIGMA_ASSET_BASE = "/assets/ark-library/figma";
@@ -123,7 +125,11 @@ export function FigmaBanner() {
     if (!scroller) return;
     const target = scroller.children[index] as HTMLElement | undefined;
     if (!target) return;
-    scroller.scrollTo({ left: target.offsetLeft, behavior });
+    // Center the slide in the viewport. On mobile (full-width slides) the
+    // offset is 0 so this matches the previous snap-start behavior.
+    const centerOffset = (scroller.clientWidth - target.offsetWidth) / 2;
+    const left = Math.max(0, target.offsetLeft - centerOffset);
+    scroller.scrollTo({ left, behavior });
   }, []);
 
   const pauseAutoplay = useCallback(() => {
@@ -168,9 +174,10 @@ export function FigmaBanner() {
     if (!scroller) return;
 
     const handleScroll = () => {
-      const width = scroller.clientWidth;
-      if (width === 0) return;
-      const next = Math.round(scroller.scrollLeft / width);
+      const firstChild = scroller.children[0] as HTMLElement | undefined;
+      const slideWidth = firstChild?.offsetWidth ?? scroller.clientWidth;
+      if (slideWidth === 0) return;
+      const next = Math.round(scroller.scrollLeft / slideWidth);
       setActiveIndex((prev) => (prev === next ? prev : next));
     };
 
@@ -238,8 +245,9 @@ export function FigmaBanner() {
       window.setTimeout(() => {
         suppressClickRef.current = false;
       }, 0);
-      const width = scroller.clientWidth || 1;
-      const nearest = Math.round(scroller.scrollLeft / width);
+      const firstChild = scroller.children[0] as HTMLElement | undefined;
+      const slideWidth = firstChild?.offsetWidth || scroller.clientWidth || 1;
+      const nearest = Math.round(scroller.scrollLeft / slideWidth);
       const clamped = Math.max(0, Math.min(slides.length - 1, nearest));
       scroller.style.scrollSnapType = "";
       goTo(clamped, "smooth");
@@ -315,6 +323,7 @@ export function FigmaBanner() {
         aria-label="ARK Library banner"
       >
         {slides.map((slide, index) => {
+          const isActive = index === activeIndex;
           const image = (
             <picture className="block aspect-video w-full overflow-hidden bg-black md:rounded-xl">
               <source media="(max-width: 767px)" srcSet={slide.mobile} />
@@ -330,11 +339,27 @@ export function FigmaBanner() {
               />
             </picture>
           );
+          const animatedImage = (
+            <m.div
+              className="h-full w-full origin-center will-change-transform"
+              animate={{
+                filter: isActive ? "blur(0px)" : "blur(6px)",
+                opacity: isActive ? 1 : 0.55,
+                scale: isActive ? 1 : 0.93,
+              }}
+              transition={{
+                duration: 0.45,
+                ease: EASE_OUT as unknown as number[],
+              }}
+            >
+              {image}
+            </m.div>
+          );
 
           return (
             <div
               key={slide.id}
-              className="relative w-full shrink-0 snap-start"
+              className="relative w-full shrink-0 snap-center md:w-[78%] md:first:ml-[11%] md:last:mr-[11%] lg:w-[72%] lg:first:ml-[14%] lg:last:mr-[14%] xl:w-[60%] xl:first:ml-[20%] xl:last:mr-[20%]"
               role="group"
               aria-roledescription="slide"
               aria-label={`${index + 1} / ${slides.length}`}
@@ -346,10 +371,10 @@ export function FigmaBanner() {
                   rel="noreferrer"
                   onClick={(event) => handleSlideClick(event, slide.linkUrl!)}
                 >
-                  {image}
+                  {animatedImage}
                 </a>
               ) : (
-                image
+                animatedImage
               )}
             </div>
           );