feat(web): IA-3 navigation, legacy redirects and top-bar inbox (FE-1)

Sidebar becomes 5 groups (overview / resources / subscriptions / organize /
system). Pending items move to a top-bar inbox with badge and grouped
dropdown. Engine panel, schedules and identity pages redirect to the task
page, its plan tab and media overview views; the download plan becomes a
second tab of the download panel. nav.test and smoke cover the new routes.

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

apps/web/app/routes/console/downloads.$id.tsx

@@ -22,7 +22,7 @@ export default function DownloadTaskPage() {
           <Button asChild variant="ghost" size="sm">
             <Link to={consolePath("downloads")}>
               <ArrowLeft />
-              下载队列
+              下载面板
             </Link>
           </Button>
         }