refactor(frontend): major rebuild — feature-sliced architecture + bug fixes + glass-morphism UI

Architecture:
- Feature-sliced directory: entities/, shared/, features/, widgets/
- Consolidated API client (shared/api/client.ts) — all endpoints in one file
- Single WebSocket manager (shared/ws/socket.ts) with typed event bus
- Extracted hooks: useAudioPlayback, useAudioTransmit, useLocalStorage, useUIState
- UI primitives moved to shared/ui/ with barrel export
- Added Skeleton, Toast, MobileTabBar components

Bug fixes (8/8):
1. useMemo→useEffect in RecordingsSubPanel (async side-effect anti-pattern)
2. ArrayBuffer.slice() before WebSocket send (shared buffer bug)
3. Proper useEffect dependency arrays throughout
4. Stable React keys (no index fallbacks)
5. onReanalyze properly awaited (Promise<void> return)
6. monitorGuild memoized with useMemo
7. localStorage validation with shape checking
8. Deleted duplicate socket logic (ws/client.ts removed)

UI polish:
- Glass-morphism design tokens (backdrop-blur, translucent cards)
- Gradient mesh background with subtle radial overlays
- Expandable sidebar + mobile bottom tab bar
- Skeleton loading placeholders
- Audio visualizer with CSS pulse animation

Deleted: src/api/, src/components/, src/hooks/, src/types/, src/ws/, src/lib/
Added: 40 new files across feature-sliced structure

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/widgets/Header.tsx

@@ -0,0 +1,51 @@
+import { Wifi, WifiOff } from "lucide-react";
+import type { DashboardTab } from "../entities/ui/types";
+import type { WsStatus } from "../shared/ws/socket";
+import type { VoiceStatus } from "../shared/api/client";
+import { Badge } from "../shared/ui";
+
+const titles: Record<DashboardTab, string> = {
+  live: "Voice, Media & Recordings",
+  messages: "Messages & Moderation",
+  analytics: "Analytics & Insights",
+};
+
+const subtitles: Record<DashboardTab, string> = {
+  live: "Join voice channels, play media, stream audio, and browse recordings.",
+  messages: "Capture, analyse, and moderate Discord messages.",
+  analytics: "Server moderation statistics and trends.",
+};
+
+interface HeaderProps {
+  activeTab: DashboardTab;
+  wsStatus: WsStatus;
+  voiceStatus: VoiceStatus;
+}
+
+export function Header({ activeTab, wsStatus, voiceStatus }: HeaderProps) {
+  return (
+    <header className="sticky top-0 z-10 border-b border-border bg-background/80 px-4 py-4 backdrop-blur md:px-8">
+      <div className="flex flex-col gap-3 md:flex-row md:items-center md:justify-between">
+        <div className="flex items-center gap-3">
+          <div>
+            <h1 className="text-xl font-bold tracking-tight">
+              <span className="text-primary">GMW</span>
+              <span className="mx-2 text-muted-foreground">·</span>
+              {titles[activeTab]}
+            </h1>
+            <p className="text-sm text-muted-foreground">{subtitles[activeTab]}</p>
+          </div>
+        </div>
+        <div className="flex flex-wrap gap-2">
+          <Badge variant={wsStatus === "connected" ? "success" : wsStatus === "error" ? "destructive" : "warning"}>
+            {wsStatus === "connected" ? <Wifi className="mr-1 h-3 w-3" /> : <WifiOff className="mr-1 h-3 w-3" />}
+            WebSocket {wsStatus}
+          </Badge>
+          <Badge variant={voiceStatus.connected ? "success" : "secondary"}>
+            Voice {voiceStatus.connected ? voiceStatus.activeChannelName || "connected" : "idle"}
+          </Badge>
+        </div>
+      </div>
+    </header>
+  );
+}