refactor(web): 前端改用 @stash/ui 组件库

- 新增本地依赖 @stash/ui（file:../../stash-ui），引入其 style.css 与设计令牌
- 页面骨架改用 Layout（contained + header/sider），搜索框改为吸顶
- 卡片/菜单/按钮/标签/头像/分页/空态/提示全部换成组件库组件
- 删除本地 iconfont 与 1400 行手写组件样式，App.css 只保留页面级样式
- 数据层、路由、过滤逻辑未改动；33 个 Rust 测试通过

stash-web/src/components/content/CesCard.tsx

@@ -1,3 +1,4 @@
+import { Card, Space, Text } from '@stash/ui'
 import type { ArticleItem } from '../../data/types'
 
 /**
@@ -10,28 +11,32 @@ type CesCardProps = {
 }
 
 export function CesCard({ item, onOpen }: CesCardProps) {
-  const content = (
-    <>
-      <img className="ces-cover" src={item.cover} alt={item.title} loading="lazy" />
-      <span className="ces-body">
-        <span className="ces-title">{item.title}</span>
-        <span className="ces-desc">{item.desc}</span>
-      </span>
-    </>
+  const body = (
+    <Space direction="column" gap="xs" align="stretch">
+      <Text strong truncate>
+        {item.title}
+      </Text>
+      <Text size="xs" tone="muted" truncate>
+        {item.desc}
+      </Text>
+    </Space>
   )
 
-  if (onOpen === undefined) {
-    return <article className="ces-card">{content}</article>
-  }
-
   return (
-    <button
-      type="button"
-      className="ces-card"
-      title={item.title}
-      onClick={() => onOpen(item.id)}
-    >
-      {content}
-    </button>
+    <Card padding="none" hoverable className="ces-card">
+      <img className="cover cover--article" src={item.cover} alt={item.title} loading="lazy" />
+      {onOpen === undefined ? (
+        <div className="ces-body">{body}</div>
+      ) : (
+        <button
+          type="button"
+          className="ces-body ces-body--button"
+          title={item.title}
+          onClick={() => onOpen(item.id)}
+        >
+          {body}
+        </button>
+      )}
+    </Card>
   )
 }