[router] add token bucket rate limiter (#9656)

sgl-router/tests/common/test_app.rs

@@ -19,12 +19,14 @@ pub fn create_test_app(
         router_config.clone(),
         client,
         router_config.max_concurrent_requests,
+        router_config.rate_limit_tokens_per_second,
     ));
 
     // Create AppState with the test router and context
     let app_state = Arc::new(AppState {
         router,
         context: app_context,
+        concurrency_queue_tx: None, // No queue for tests
     });
 
     // Configure request ID headers (use defaults if not specified)