Initial commit: party-mix-app with prefetch cache, audio preload optimizations

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

apps/bot/src/config.ts

@@ -0,0 +1,8 @@
+export const config = {
+  botToken: process.env.BOT_TOKEN ?? '',
+  backendUrl: process.env.BACKEND_URL ?? 'http://localhost:8080',
+} as const
+
+if (!config.botToken) {
+  throw new Error('BOT_TOKEN environment variable is required')
+}