Cron: suppress fallback main summary for delivery-target errors (openclaw#24074) thanks @Takhoffman

Verified:
- pnpm build
- pnpm check
- pnpm test:macmini

Co-authored-by: Takhoffman <781889+Takhoffman@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/cron/types.ts

@@ -47,6 +47,8 @@ export type CronRunTelemetry = {
 export type CronRunOutcome = {
   status: CronRunStatus;
   error?: string;
+  /** Optional classifier for execution errors to guide fallback behavior. */
+  errorKind?: "delivery-target";
   summary?: string;
   sessionId?: string;
   sessionKey?: string;