feat(web): FE overhaul — SWR centralized data layer + dashboard + islands

- Add SWR foundation (lib/fetcher, lib/swr, lib/api) with typed
  hooks: useSections/useDocuments/useSearch/useRelated/useRevisions/useQueueStatus
- Replace ad-hoc useEffect+fetch in Header/Sidebar/CommandMenu/search
  with SWR (dedup 4s, focus throttle 10s, debounced search 180ms)
- Doc page: RelatedGrid + RevisionList as SWR client islands (RSC hero stays)
- DocForm: SWR mutate on create/update for live sidebar invalidation
- New APIs: /api/related, /api/revisions, /api/tags, /api/queue/status,
  /api/docs filtering (?section=&status=)
- New UI: DocumentCard, SectionCard, SearchBar, TagCloud, QueueBadge,
  EmptyState, dashboard (/dashboard with QueueStrip live + section stats)
- Layout wraps SWRProvider; no TanStack code (SWR-only per spec)
- Verified: next build passes (16.3.4 Turbopack), no manual fetch sprawl remains

Co-Authored-By: internal-model

apps/web/app/hooks/useQueueStatus.ts

@@ -0,0 +1,27 @@
+"use client";
+
+import useSWR from "swr";
+import { fetcher } from "@/lib/fetcher";
+
+export interface QueueStatus {
+  waiting: number;
+  active: number;
+  completed: number;
+  failed: number;
+  delayed: number;
+}
+
+export function useQueueStatus(enabled = false) {
+  return useSWR<QueueStatus>(enabled ? "/api/queue/status" : null, fetcher, {
+    refreshInterval: 5_000,
+    dedupingInterval: 4_000,
+    revalidateOnFocus: false,
+  });
+}
+
+export function useTags(limit = 30) {
+  const key = `/api/tags?limit=${limit}`;
+  return useSWR<{ tags: { tag: string; count: number }[] }>(key, fetcher, {
+    revalidateOnFocus: false,
+  });
+}