iter(g29): 新增 carousel 轮播组件

packages/skin/ui/ui.css

@@ -2071,3 +2071,74 @@ button.ua-step-dot:hover {
     transition: none;
   }
 }
+
+/* —— 轮播 —— */
+.ua-carousel {
+  position: relative;
+  overflow: hidden;
+  border-radius: var(--ua-radius-md);
+  background: var(--ua-color-surface);
+  outline: none;
+}
+.ua-carousel:focus-visible {
+  box-shadow: 0 0 0 2px color-mix(in srgb, var(--ua-color-accent) 45%, transparent);
+}
+.ua-carousel-track {
+  display: flex;
+  height: 100%;
+  transition: transform 0.32s ease;
+}
+.ua-carousel-slide {
+  flex: 0 0 100%;
+  display: flex;
+}
+.ua-carousel-arrow {
+  position: absolute;
+  top: 50%;
+  transform: translateY(-50%);
+  width: 28px;
+  height: 28px;
+  border: 1px solid var(--ua-color-border);
+  border-radius: 50%;
+  background: var(--ua-color-bg);
+  color: var(--ua-color-text);
+  font-size: var(--ua-font-size-lg);
+  line-height: 1;
+  cursor: pointer;
+  opacity: 0;
+  transition: opacity 0.15s ease;
+}
+.ua-carousel-prev { left: var(--ua-space-2); }
+.ua-carousel-next { right: var(--ua-space-2); }
+.ua-carousel:hover .ua-carousel-arrow,
+.ua-carousel:focus-within .ua-carousel-arrow { opacity: 1; }
+.ua-carousel-arrow:hover { background: var(--ua-color-surface); }
+.ua-carousel-dots {
+  position: absolute;
+  left: 0;
+  right: 0;
+  bottom: var(--ua-space-2);
+  display: flex;
+  gap: var(--ua-space-1);
+  justify-content: center;
+}
+.ua-carousel-dot {
+  width: 6px;
+  height: 6px;
+  padding: 0;
+  border: none;
+  border-radius: 50%;
+  background: var(--ua-color-border);
+  cursor: pointer;
+  transition: width 0.2s ease, background 0.2s ease;
+}
+.ua-carousel-dot-active {
+  width: 16px;
+  border-radius: var(--ua-radius-sm);
+  background: var(--ua-color-accent);
+}
+@media (prefers-reduced-motion: reduce) {
+  .ua-carousel-track,
+  .ua-carousel-dot,
+  .ua-carousel-arrow { transition: none; }
+}