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/api/feeds.ts

@@ -6,6 +6,7 @@ import {
   type FeedSourceCreate,
   type FeedSourceUpdate,
   Id,
+  Observation,
 } from "@umt/contracts";
 import { z } from "zod";
 import { TTL_SECOND } from "~/lib/api.ts";
@@ -40,6 +41,18 @@ export function useFeed(id: string | null, poll = false) {
   });
 }
 
+const ObservationPage = cursorPage(Observation);
+
+/** RSS 最近条目(观察记录,新的在前);只在详情打开时请求 */
+export function useFeedObservations(feedId: string | null, limit = 20) {
+  return useQuery({
+    queryKey: [...feedKeys.all, "observations", feedId, limit] as const,
+    enabled: !!feedId,
+    queryFn: ({ signal }) =>
+      apiParsed(ObservationPage, "/api/v1/observations", { params: { feedId: feedId ?? "", limit }, signal }),
+  });
+}
+
 /** 同站判定的主机键(与服务端 feedDefaultsForSite 一致):去 www.,取最后两级;IP 原样 */
 export function feedHostKey(u: string): string | null {
   try {