iter(g136): 新增链接组件 link

packages/skin/ui/ui.css

@@ -4308,3 +4308,55 @@ h5.ua-type-title { font-size: var(--ua-font-size-md); }
     transition: none;
   }
 }
+
+/* —— 链接：颜色走令牌，悬停下划线渐进显现 —— */
+.ua-link {
+  display: inline-flex;
+  align-items: baseline;
+  gap: 2px;
+  color: var(--ua-color-accent);
+  text-decoration: none;
+  text-underline-offset: 2px;
+  text-decoration-thickness: 1px;
+  transition: color 0.15s ease, text-decoration-color 0.15s ease;
+  cursor: pointer;
+}
+.ua-link:hover {
+  text-decoration: underline;
+}
+.ua-link:focus-visible {
+  outline: 2px solid var(--ua-color-accent);
+  outline-offset: 2px;
+  border-radius: var(--ua-radius-sm);
+}
+.ua-link.is-muted {
+  color: var(--ua-color-text-muted);
+}
+.ua-link.is-muted:hover {
+  color: var(--ua-color-text);
+}
+.ua-link.is-disabled {
+  color: var(--ua-color-text-muted);
+  cursor: not-allowed;
+  text-decoration: none;
+}
+.ua-link-icon {
+  font-size: 0.85em;
+  line-height: 1;
+}
+.ua-visually-hidden {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  margin: -1px;
+  padding: 0;
+  overflow: hidden;
+  clip: rect(0 0 0 0); /* 只给读屏，视觉不可见 */
+  white-space: nowrap;
+  border: 0;
+}
+@media (prefers-reduced-motion: reduce) {
+  .ua-link {
+    transition: none;
+  }
+}