feat(streaming): add Screen Streaming plugin with WebRTC

New plugin: browser-based screen sharing via Chrome Screen Capture API.
Multi-stream grid layout (Rustdesk-style tiles) with live previews.

- Server: WebSocket signaling at /ws/streaming (SDP/ICE relay)
- Server: http.createServer for WebSocket attachment
- Frontend: StreamingTab with broadcaster/viewer modes
- Frontend: tile grid, fullscreen viewer, LIVE badges
- Supports multiple concurrent streams
- Peer-to-peer video via WebRTC (no video through server)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/App.tsx

@@ -2,6 +2,7 @@ import { useState, useEffect, useRef } from 'react';
 import RadioTab from './plugins/radio/RadioTab';
 import SoundboardTab from './plugins/soundboard/SoundboardTab';
 import LolstatsTab from './plugins/lolstats/LolstatsTab';
+import StreamingTab from './plugins/streaming/StreamingTab';
 
 interface PluginInfo {
   name: string;
@@ -14,6 +15,7 @@ const tabComponents: Record<string, React.FC<{ data: any }>> = {
   radio: RadioTab,
   soundboard: SoundboardTab,
   lolstats: LolstatsTab,
+  streaming: StreamingTab,
 };
 
 export function registerTab(pluginName: string, component: React.FC<{ data: any }>) {
@@ -85,6 +87,7 @@ export default function App() {
     events: '\u{1F4C5}',
     games: '\u{1F3B2}',
     gamevote: '\u{1F3AE}',
+    streaming: '\u{1F4FA}',
   };
 
   return (