feat: migrate and redesign dashboard to modern React

- Full rewrite of legacy vanilla JS UI into React SPA
- Implement modern design system using Tailwind CSS and shadcn/ui primitives
- Create typed API modules and hooks for voice, media, and moderation
- Add new features: separated Music and Screen Share panels, Image Grid
- Implement unified WebSocket hook for real-time state and PCM audio
- Improve visualizer with smooth CSS transitions and live state sync
- Add __dirname polyfill for ES module compatibility
- Ensure responsive layout for mobile and desktop

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/api/voice.ts

@@ -0,0 +1,33 @@
+import { request } from "./client";
+import type { Channel, Guild, VoiceStatus } from "../types/voice";
+
+export function getGuilds(): Promise<Guild[]> {
+  return request<Guild[]>('/api/guilds');
+}
+
+export function getVoiceChannels(guildId: string): Promise<Channel[]> {
+  return request<Channel[]>(`/api/guilds/${guildId}/voice-channels`);
+}
+
+export function getTextChannels(guildId: string): Promise<Channel[]> {
+  return request<Channel[]>(`/api/guilds/${guildId}/channels`);
+}
+
+export function getThreads(guildId: string): Promise<Channel[]> {
+  return request<Channel[]>(`/api/guilds/${guildId}/threads`);
+}
+
+export function getVoiceStatus(): Promise<VoiceStatus> {
+  return request<VoiceStatus>('/api/status');
+}
+
+export function connectVoice(guildId: string, channelId: string): Promise<VoiceStatus> {
+  return request<VoiceStatus>('/api/connect', {
+    method: 'POST',
+    body: JSON.stringify({ guildId, channelId }),
+  });
+}
+
+export function disconnectVoice(): Promise<VoiceStatus> {
+  return request<VoiceStatus>('/api/disconnect', { method: 'POST' });
+}