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/sidebar/Sidebar.tsx

@@ -1,5 +1,6 @@
 import type { Project } from '../../api'
-import type { NavModel, NavTarget } from '../../data/nav'
+import type { NavTarget } from '../../data/nav'
+import type { Category } from '../../data/types'
 import { CategoryNav } from './CategoryNav'
 import { ProfileCard } from './ProfileCard'
 import { ServicePanel } from './ServicePanel'
@@ -10,8 +11,8 @@ import { ServicePanel } from './ServicePanel'
  */
 type SidebarProps = {
   projects: Project[]
-  /** 侧栏导航数据，来自内容库 */
-  nav: NavModel
+  /** 内容目录；侧栏直接由它派生 */
+  categories: Category[]
   live: boolean
   refreshing: boolean
   onRefresh: () => void
@@ -22,7 +23,7 @@ type SidebarProps = {
 
 export function Sidebar({
   projects,
-  nav,
+  categories,
   live,
   refreshing,
   onRefresh,
@@ -42,7 +43,7 @@ export function Sidebar({
       />
 
       <CategoryNav
-        nav={nav}
+        categories={categories}
         activeCategoryId={activeCategoryId}
         activeGroupId={activeGroupId}
         onNavigate={onNavigate}