feat(frontend): rebuild as SSR with server-authoritative shared state

Rombak total alur data frontend: dari static-export CSR (tiap browser
fetch sendiri + akumulasi state voice per-tab) jadi server-side rendering.

Frontend (Next.js):
- next.config: output export -> standalone; halaman jadi server components
- server data layer baru src/lib/api/server.ts (GMW_BACKEND_URL, no window)
- dashboard/media/messages/moderation/recordings/voice page -> RSC yang
  fetch backend di render-time, seed ke client view (SWR fallbackData)
- hook-hook utama terima initialData -> first paint data server, revalidate
  SWR setelahnya, tanpa spinner-blank-load
- messages: guild/channel/tab/selected dibaca dari URL di server, page awal
  di-fetch server-side

Shared realtime state (voice) server-authoritative:
- backend src/modules/voice/live-speaker.ts: agregat voice_active_user dari
  gateway jadi snapshot authoritatif (single source of truth semua browser)
- GET /api/voice/status kini include activeSpeakers
- WS initial states kirim voice_state snapshot saat connect (late join
  langsung dapat state yang sama, bukan daftar kosong)
- useSpeakers seed dari server snapshot + voice_state full-replace +
  voice_active_user delta upsert

Deploy:
- flake.nix: frontend package build SSR standalone (server.js wrapper,
  GMW_FRONTEND_PORT=4017); proxy nginx template proxy / -> Next server,
  /api + /ws tetap ke backend :4001

services/frontend/src/components/media/music-player.tsx

@@ -18,12 +18,16 @@ import {
 } from "@/hooks";
 import type { WsHook } from "@/lib/ws-hook";
 
+import type { MediaState } from "@/lib/types";
+
 interface MusicPlayerProps {
   ws: WsHook;
+  /** Server-fetched media snapshot used to seed the first render. */
+  initialData?: MediaState;
 }
 
-export function MusicPlayer({ ws }: MusicPlayerProps) {
-  const { data: mediaState } = useMediaState();
+export function MusicPlayer({ ws, initialData }: MusicPlayerProps) {
+  const { data: mediaState } = useMediaState(initialData);
   const queueMut = useMediaQueue();
   const skipMut = useMediaSkip();
   const stopMut = useMediaStop();

services/frontend/src/components/moderation/moderation-section.tsx

@@ -17,7 +17,11 @@ import { EmptyState, LoadingSkeleton } from "@/components/shared";
 import { Badge } from "@/components/ui/badge";
 import { useModerationActions, useModerationStats } from "@/hooks";
 import { renderMessageContent } from "@/lib/format";
-import type { ModerationAction, ModerationActionType } from "@/lib/types";
+import type {
+  ModerationAction,
+  ModerationActionType,
+  ModerationStats,
+} from "@/lib/types";
 import { cn } from "@/lib/utils";
 
 const ACTION_META: Record<
@@ -82,13 +86,20 @@ const EMPTY_ACTION_RATE = {
   failed_rate: 0,
 };
 
-export function ModerationSection() {
+export function ModerationSection({
+  initialStats,
+  initialActions,
+}: {
+  initialStats?: ModerationStats;
+  initialActions?: ModerationAction[];
+} = {}) {
   const [status, setStatus] = useState<string>("");
   const [actionType, setActionType] = useState<string>("");
-  const { data: stats } = useModerationStats();
+  const { data: stats } = useModerationStats(initialStats);
   const { data: actions, isLoading: actionsLoading } = useModerationActions(
     status,
     actionType,
+    initialActions,
   );
 
   const s = stats ?? EMPTY_ACTION_RATE;
@@ -159,7 +170,7 @@ export function ModerationSection() {
       </div>
 
       {/* Timeline */}
-      {actionsLoading ? (
+      {actionsLoading && !actions ? (
         <LoadingSkeleton count={6} height="h-16" />
       ) : !actions || actions.length === 0 ? (
         <GlassCard className="p-6">