feat(base): add 429 retry with fixed delay for all providers

Retry up to 2 times with 2s delay before falling back to next URL.

Made-with: Cursor

open-sse/config/constants.js

@@ -461,6 +461,12 @@ export const DEFAULT_MAX_TOKENS = 64000;
 // Minimum max tokens for tool calling (to prevent truncated arguments)
 export const DEFAULT_MIN_TOKENS = 32000;
 
+// Retry config for 429 responses (used by BaseExecutor)
+export const RETRY_CONFIG = {
+  maxAttempts: 2,
+  delayMs: 2000
+};
+
 // HTTP status codes
 export const HTTP_STATUS = {
   BAD_REQUEST: 400,