feat(calendar): document outbox retention policy

docs/DEPLOYMENT_OPERATOR_GUIDE.md

@@ -153,16 +153,24 @@ on throwaway databases.
 | --- | --- | --- |
 | `REDIS_URL` | `redis://redis:6379/0` | Celery broker/result backend when async workers are enabled. |
 | `CELERY_ENABLED` | `false` | Local/dev can send synchronously. Production campaign delivery should run workers and set this to `true`. |
-| `CELERY_QUEUES` | `send_email,append_sent,default` | Queue list expected by worker/process manager definitions. |
+| `CELERY_QUEUES` | `send_email,append_sent,notifications,calendar,default` | Queue list expected by worker/process manager definitions. The Calendar queue drains durable external-calendar operations. |
 
 Worker command:
 
 ```bash
 python -m celery -A govoplan_core.celery_app:celery worker \
-  --queues send_email,append_sent,default \
+  --queues send_email,append_sent,notifications,calendar,default \
   --loglevel INFO
 ```
 
+Run Celery beat as a separately supervised process. Its built-in one-minute
+schedule recovers Calendar outbox rows left behind by broker failures, process
+crashes, and expired worker leases:
+
+```bash
+python -m celery -A govoplan_core.celery_app:celery beat --loglevel INFO
+```
+
 ### Storage
 
 | Setting | Default | Notes |
@@ -275,7 +283,7 @@ the checked in `.env.example`. It runs:
 - explicit `ENABLED_MODULES`
 - explicit migrations and `--with-dev-data` bootstrap
 - API via the module-aware devserver
-- a Celery worker for `send_email,append_sent,default`
+- a Celery worker for `send_email,append_sent,notifications,calendar,default`
 - WebUI through the Vite dev server
 - durable local files under `runtime/production-like/files`