refactor(fe): replace TanStack Query with SWR + UI/data cleanup

Rombak data layer frontend:
- Hapus @tanstack/react-query (package.json, lockfile, provider di
  dashboard layout) — ganti SWR 2.4.2 + SWRConfig (revalidateOnFocus
  false, deduping 10s, no retry on 404)
- Semua hooks data ditulis ulang ke useSWR; useAction() helper baru
  pengganti useMutation dengan surface kompatibel (mutate/mutateAsync/
  isPending/error)
- useMessages + useMessagesHasMore share satu SWR key — probe cursor
  yang tadinya dobel fetch API sekarang deduped
- WS sync (messages/media/recordings) pindah dari queryClient ke
  SWR mutate dengan filter key + revalidate:false
- useMessageSearch() dipakai search-panel & search-overlay; search
  overlay backdrop div -> button (fix a11y lint)

Rapikan UI + isi data:
- Tab stats recordings: placeholder 'coming soon' diganti stat asli
  (total, ukuran, speaker unik, top speakers)
- Empty states konsisten via EmptyState (images/review/recordings),
  EmptyState terima className
- biome check --write: 0 error, 8 warning pre-existing
- Verifikasi: tsc --noEmit PASS, next build PASS (11 halaman static),
  API live dicek — semua endpoint dashboard/messages/guilds/config/
  voice/media/recordings/review balikin data

services/frontend/src/components/shared/empty-state.tsx

@@ -3,20 +3,26 @@
 import type { LucideIcon } from "lucide-react";
 import { Inbox } from "lucide-react";
 import { GlassPanel } from "@/components/glass/panel";
+import { cn } from "@/lib/utils";
 
 interface EmptyStateProps {
   icon?: LucideIcon;
   title?: string;
   description?: string;
+  className?: string;
 }
 
 export function EmptyState({
   icon: Icon = Inbox,
   title = "No data yet",
   description = "Nothing to display here yet.",
+  className,
 }: EmptyStateProps) {
   return (
-    <GlassPanel dense className="flex flex-col items-center gap-2 py-12">
+    <GlassPanel
+      dense
+      className={cn("flex flex-col items-center gap-2 py-12", className)}
+    >
       <Icon className="size-8 text-text-secondary/20" />
       <p className="text-sm text-text-secondary/60">{title}</p>
       <p className="text-xs text-text-secondary/40">{description}</p>