fix: Remove incorrect Bun import and add proper type declarations

src/server.ts

@@ -1,7 +1,12 @@
-import { Bun } from 'bun';
+/// <reference types="bun-types" />
 import { CommandService } from './services/command';
 import { ResponseQueue } from './services/response-queue';
 
+// Bun is available globally when running under Bun runtime
+declare global {
+    var Bun: typeof import('bun');
+}
+
 const PORT = 3007;
 
 type WebhookPayload = {