feat: merge Voice, Media, and Recordings into unified Live panel

- New LivePanel component combines voice bridge, media player, screen share, and recordings
- Single page layout: voice controls → audio visualizer + active speakers → now playing → music/screen/recordings tabs
- Reduced tabs from 6 to 4: Live, Messages, Analytics, Review
- Sidebar updated with new tab structure
- Default tab changed from 'voice' to 'live'
- Cleaner compact layout with icon buttons and inline controls
- Recordings sub-panel with user avatars, status badges, and download buttons

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

frontend/src/components/layout/Header.tsx

@@ -5,19 +5,15 @@ import type { VoiceStatus } from "../../types/voice";
 import { Badge } from "../ui/badge";
 
 const titles: Record<DashboardTab, string> = {
-  voice: "Voice Control",
-  media: "Media Player",
+  live: "Voice, Media & Recordings",
   messages: "Messages & Moderation",
-  recordings: "Voice Recordings",
   analytics: "Analytics & Insights",
   review: "Moderation Review",
 };
 
 const subtitles: Record<DashboardTab, string> = {
-  voice: "Join voice channels and stream audio.",
-  media: "Queue music, videos, and screen share.",
+  live: "Join voice channels, play media, stream audio, and browse recordings.",
   messages: "Capture, analyse, and moderate Discord messages.",
-  recordings: "Browse recorded voice segments.",
   analytics: "Server moderation statistics and trends.",
   review: "Review AI-flagged messages for moderation.",
 };