fix(letta-api): restore 429 rethrow in rejectApproval

Re-throws rate limit errors so callers bail out early instead of
hammering the API in a tight loop. This was accidentally dropped
during the merge.

src/tools/letta-api.ts

@@ -550,6 +550,12 @@ export async function rejectApproval(
       log.warn(`Approval already resolved for tool call ${approval.toolCallId}`);
       return true;
     }
+    // Re-throw rate limit errors so callers can bail out early instead of
+    // hammering the API in a tight loop.
+    if (err?.status === 429) {
+      log.error('Failed to reject approval:', e);
+      throw e;
+    }
     log.error('Failed to reject approval:', e);
     return false;
   }