fix(kiro): canonicalize tool history and route API keys correctly

Route API-key inference through Amazon Q first, enforce adjacent
one-to-one tool use/result pairs after session replay, and treat
payload-invalid HTTP 400 as terminal.

open-sse/executors/base.js

@@ -126,7 +126,7 @@ export class BaseExecutor {
     for (let urlIndex = 0; urlIndex < fallbackCount; urlIndex++) {
       const url = this.buildUrl(model, stream, urlIndex, credentials);
       const transformedBody = this.transformRequest(model, body, stream, credentials);
-      const headers = this.buildHeaders(credentials, stream);
+      const headers = this.buildHeaders(credentials, stream, url);
 
       if (!retryAttemptsByUrl[urlIndex]) retryAttemptsByUrl[urlIndex] = 0;