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/ItemDetailView.tsx

@@ -1,7 +1,6 @@
 import type { ItemDetailModel } from '../../data/detail'
 import type { RelatedItem } from '../../data/types'
 import { ExternalIcon, EyeIcon, ShareIcon, ThumbUpIcon } from '../common/Icon'
-import { ArrowLeftIcon } from '../common/Icon'
 import { RelatedList } from './RelatedList'
 
 /**
@@ -30,7 +29,6 @@ export function ItemDetailView({
     <div className="detail-view item-view">
       <div className="detail-nav card-box">
         <button type="button" className="detail-back" onClick={onBack}>
-          <ArrowLeftIcon />
           返回
         </button>
         <span className="detail-breadcrumb">{breadcrumb}</span>