feat(web): 地址栏驱动视图，刷新详情页不再回首页

- 新增 data/view.ts 与 useViewRoute：视图与地址双向同步，支持前进后退
- 条目地址带上所属分组，刷新 / 收藏后「返回」有确定落点
- 服务端只把 /c/** 回落到 index.html，其余路径仍返回 404
- 明细页返回按钮去掉左侧箭头图标

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

@@ -1,5 +1,4 @@
 import { categoryCount, type Category } from '../../data/types'
-import { ArrowLeftIcon } from '../common/Icon'
 import { AppGrid } from './AppGrid'
 import { CesCardGrid } from './CesCardGrid'
 import { GroupBlock } from './GroupBlock'
@@ -68,7 +67,6 @@ export function DetailView({ category, groupId, onBack, onOpenItem }: DetailView
     <div className="detail-view">
       <div className="detail-nav card-box">
         <button type="button" className="detail-back" onClick={onBack}>
-          <ArrowLeftIcon />
           返回首页
         </button>
         <span className="detail-breadcrumb">{breadcrumb}</span>