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>

CHANGELOG.md

@@ -78,6 +78,7 @@ Docs: https://docs.openclaw.ai
 - Cron/Timer: keep a watchdog recheck timer armed while `onTimer` is actively executing so the scheduler continues polling even if a due-run tick stalls for an extended period. (#23628) Thanks @dsgraves.
 - Cron/Run log: clean up settled per-path run-log write queue entries so long-running cron uptime does not retain stale promise bookkeeping in memory.
 - Cron/Run log: harden `cron.runs` run-log path resolution by rejecting path-separator `id`/`jobId` inputs and enforcing reads within the per-cron `runs/` directory.
+- Cron/Announce: when announce delivery target resolution fails (for example multiple configured channels with no explicit target), skip injecting fallback `Cron (error): ...` into the main session so runs fail cleanly without accidental last-route sends. (#24074)
 - Cron/Isolation: force fresh session IDs for isolated cron runs so `sessionTarget="isolated"` executions never reuse prior run context. (#23470) Thanks @echoVic.
 - Plugins/Install: strip `workspace:*` devDependency entries from copied plugin manifests before `npm install --omit=dev`, preventing `EUNSUPPORTEDPROTOCOL` install failures for npm-published channel plugins (including Feishu and MS Teams).
 - Feishu/Plugins: restore bundled Feishu SDK availability for global installs and strip `openclaw: workspace:*` from plugin `devDependencies` during plugin-version sync so npm-installed Feishu plugins do not fail dependency install. (#23611, #23645, #23603)