feat(web): regroup console nav into 7 groups, split downloads/plans/tasks, add legacy redirects

- Sidebar: 概览/资源/订阅/下载/整理/Agent/系统, 18 items (+ 定时任务); single
  active item via findNavItem; 待处理 badge; collapsed rail groups; mobile drawer
  shares NAV_GROUPS.
- New pages: /downloads (queue + cache watermark header), /downloads/plans,
  /downloads/:id, /tasks (business tasks only) + /tasks/:id detail, /rules.
- Legacy links: ?tab= on tasks/subscriptions/sources redirect via clientLoader;
  /tasks/:downloadId falls back to /downloads/:id.
- List filters in URL query; settingsPath() helper for settings deep links.
- Copy per glossary (待处理, 收录策略, 引擎面板, 文件管理, 版本目标).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/web/app/routes/console/files.tsx

@@ -442,7 +442,7 @@ export default function FilesPage() {
           plain
           icon={FolderTree}
           title="还没有库根"
-          description="在系统设置里登记库根或下载器路径映射。"
+          description="在设置里登记库根或下载器路径映射。"
           className="px-2 py-8"
         />
       ) : null}
@@ -614,7 +614,7 @@ export default function FilesPage() {
   return (
     <>
       <PageHeader
-        title="文件"
+        title="文件管理"
         description="已登记的库根与下载目录。删除先进回收站,改名同步更新资产。"
         actions={
           <>