feat: Soundboard Plugin + Radio Globe Fixes

- Add Soundboard plugin (full Jukebox port): server + frontend + CSS
- Fix Radio Globe: swap geo coords (API returns [lng,lat] not [lat,lng])
- Fix Radio stations showing "Unbekannt": use item.page.title + fix channel ID regex
- Add DirectMessages + MessageContent intents for DM commands
- Register SoundboardTab in App.tsx with scoped theme/card-size CSS vars

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

web/src/App.tsx

@@ -1,5 +1,6 @@
 import { useState, useEffect, useRef } from 'react';
 import RadioTab from './plugins/radio/RadioTab';
+import SoundboardTab from './plugins/soundboard/SoundboardTab';
 
 interface PluginInfo {
   name: string;
@@ -10,6 +11,7 @@ interface PluginInfo {
 // Plugin tab components
 const tabComponents: Record<string, React.FC<{ data: any }>> = {
   radio: RadioTab,
+  soundboard: SoundboardTab,
 };
 
 export function registerTab(pluginName: string, component: React.FC<{ data: any }>) {