feat(guild): fail fast when center auth env is missing

src/main.ts

@@ -6,7 +6,23 @@ import { AppModule } from './app.module';
 import { createRequestContextMiddleware } from './common/request-context.middleware';
 import { MetricsService } from './common/metrics.service';
 
+function requireEnv(name: string): string {
+  const value = process.env[name];
+  if (!value || value.trim() === '') {
+    throw new Error(`Missing required env: ${name}`);
+  }
+  return value;
+}
+
+function validateEnv(): void {
+  requireEnv('CENTER_BASE_URL');
+  requireEnv('CENTER_API_KEY');
+  requireEnv('GUILD_NODE_ID');
+}
+
 async function bootstrap() {
+  validateEnv();
+
   const app = await NestFactory.create(AppModule);
   app.setGlobalPrefix('api');
   const metrics = app.get(MetricsService);