feat(smart-proxy): add background concurrent certificate provisioning with per-domain timeouts and concurrency control

ts/proxies/smart-proxy/utils/index.ts

@@ -17,6 +17,9 @@ export * from './route-utils.js';
 // Export default certificate generator
 export { generateDefaultCertificate } from './default-cert-generator.js';
 
+// Export concurrency semaphore
+export { ConcurrencySemaphore } from './concurrency-semaphore.js';
+
 // Export additional functions from route-helpers that weren't already exported
 export {
   createApiGatewayRoute,