feat: 新增接口一览页 /interface，滚动信息区域收窄

- 新页面 /interface：按用途分组的接口表（方法 / 路径 / 说明 / 权限），
  用库里的 Card + Table + Tag 排；服务端 SPA 路由加入该路径
- 侧边栏「查看接口」不再直接打开 /api/projects 的原始 JSON，改指到该页面
- 页头滚动信息宽度上限 720px（原来铺满，约减少 1/3）

stash-web/src/AppNext.tsx

@@ -18,6 +18,7 @@ import { ItemEditor } from './components/content/ItemEditor'
 import { PosterGrid } from './components/content/PosterGrid'
 import { SectionCard } from './components/content/SectionCard'
 import { SiteHeader } from './components/header/SiteHeader'
+import { ApiDocs } from './components/api/ApiDocs'
 import { GroupMark } from './components/common/GroupMark'
 import { LoginDialog } from './components/auth/LoginDialog'
 import { ProfileCard } from './components/sidebar/ProfileCard'
@@ -59,9 +60,11 @@ type Route =
   | { kind: 'home' }
   | { kind: 'group'; key: string }
   | { kind: 'item'; key: string; itemId: string }
+  | { kind: 'api' }
 
 function parseRoute(pathname: string): Route {
   const segments = pathname.split('/').filter(Boolean)
+  if (segments[0] === 'interface') return { kind: 'api' }
   if (
     (segments[0] === 'g' || segments[0] === 'c') &&
     segments[1] !== undefined
@@ -358,7 +361,7 @@ export default function AppNext() {
   }, [manage.groups])
 
   const activeKey =
-    route.kind === 'home'
+    route.kind === 'home' || route.kind === 'api'
       ? 'home'
       : route.kind === 'group'
         ? `g:${route.key}`
@@ -740,6 +743,7 @@ export default function AppNext() {
           )}
 
           {route.kind === 'home' && renderHome()}
+          {route.kind === 'api' && <ApiDocs />}
           {route.kind === 'group' && renderGroupPage(route.key)}
           {route.kind === 'item' && renderItemPage(route.key, route.itemId)}
         </div>