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/hooks/use-action.ts

@@ -0,0 +1,55 @@
+import { useCallback, useRef, useState } from "react";
+
+export interface UseActionState {
+  isPending: boolean;
+  error: Error | null;
+}
+
+/**
+ * A lightweight mutation hook with a TanStack-compatible surface
+ * ({ mutate, mutateAsync, isPending, error }) built on plain state —
+ * the SWR replacement for useMutation. Fire-and-forget via `mutate`,
+ * await the result via `mutateAsync`.
+ *
+ * `onSuccess` receives (data, args) and may perform SWR cache updates
+ * (e.g. `mutate(key, data, { revalidate: false })`).
+ */
+export function useAction<TArgs = void, TResult = unknown>(
+  fn: (args: TArgs) => Promise<TResult>,
+  options?: {
+    onSuccess?: (data: TResult, args: TArgs) => void | Promise<void>;
+  },
+) {
+  const [state, setState] = useState<UseActionState>({
+    isPending: false,
+    error: null,
+  });
+
+  const fnRef = useRef(fn);
+  fnRef.current = fn;
+  const onSuccessRef = useRef(options?.onSuccess);
+  onSuccessRef.current = options?.onSuccess;
+
+  const run = useCallback(async (args?: TArgs): Promise<TResult> => {
+    setState({ isPending: true, error: null });
+    try {
+      const data = await fnRef.current(args as TArgs);
+      await onSuccessRef.current?.(data, args as TArgs);
+      setState({ isPending: false, error: null });
+      return data;
+    } catch (err) {
+      setState({ isPending: false, error: err as Error });
+      throw err;
+    }
+  }, []);
+
+  return {
+    mutate: (args?: TArgs) => {
+      void run(args);
+    },
+    mutateAsync: run,
+    isPending: state.isPending,
+    error: state.error,
+    reset: () => setState({ isPending: false, error: null }),
+  };
+}