feat(web): nav regroup, site RSS tab and site types (IA-2)

- sidebar: 概览 / 获取 / 整理 / 系统. Tasks moves to 系统; sites,
  subscriptions and rules form the 获取 group (ACQUIRE_GROUP_TITLE in
  nav.ts, the single place to rename it); standalone RSS nav item removed
- site detail gets an RSS tab with everything the RSS page had (create,
  edit, enable, fetch now, fetch state) plus recent items; tabs and
  header actions follow the site's capabilities
- old /console/sources links redirect to the site's RSS tab (?feed= looks
  up the owning site) or the site list; task links to RSS point at sites
- site list shows and filters by type; add-site wizard starts with a type
  step (PT still picks from the definition library; public BT / custom
  RSS source only need name, URL and RSS URL)

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

apps/web/app/components/sites/search-default-dialog.tsx

@@ -42,7 +42,7 @@ export function SearchDefaultDialog({
     setMode(settings.data.search?.defaultSiteMode ?? "default");
     setIds(settings.data.search?.siteIds ?? []);
   }, [open, settings.data]);
-  const enabled = sites.filter((s) => s.enabled);
+  const enabled = sites.filter((s) => s.enabled && s.capabilities.includes("search"));
 
   const save = () =>
     update.mutate(