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>

server/src/index.ts

@@ -5,6 +5,7 @@ import { addSSEClient, removeSSEClient, sseBroadcast, getSSEClientCount } from '
 import { loadState, getFullState } from './core/persistence.js';
 import { getPlugins, registerPlugin, PluginContext } from './core/plugin.js';
 import radioPlugin from './plugins/radio/index.js';
+import soundboardPlugin from './plugins/soundboard/index.js';
 
 // ── Config ──
 const PORT = Number(process.env.PORT ?? 8080);
@@ -101,6 +102,7 @@ client.once('ready', async () => {
 async function boot(): Promise<void> {
   // ── Register plugins ──
   registerPlugin(radioPlugin);
+  registerPlugin(soundboardPlugin);
 
   // Init all plugins
   for (const p of getPlugins()) {