feat(worker): Add db_worker service with automatic restart and logging

feat(task_overview): Display generated series in task overview
docs(README): Update documentation for background task workers and troubleshooting

README.md

@@ -11,6 +11,59 @@ Running locally (development)
   COMPOSE_ENV=dev docker compose -f docker/docker-compose.prod.yml -f docker/docker-compose.dev.yml up -d --build
   ```
 
+Background task workers (automatic)
+- The compose stack now includes a dedicated `worker` service which runs:
+
+  ```sh
+  python manage.py db_worker
+  ```
+
+- This means workers start automatically with `docker compose up` and restart on failure.
+- To inspect worker logs:
+
+  ```sh
+  docker compose logs -f worker
+  ```
+
+- To scale workers (for higher throughput):
+
+  ```sh
+  docker compose up -d --scale worker=2
+  ```
+
+Troubleshooting `SIGKILL` when running manually
+- A `SIGKILL` on `db_worker` is usually the kernel OOM killer (out-of-memory), not a Django exception.
+- Check kernel OOM events:
+
+  ```sh
+  dmesg -T | grep -i -E "killed process|out of memory|oom"
+  ```
+
+- If OOM is confirmed, prefer running worker inside compose (managed restart + container limits), reduce concurrency/parallel services, or add memory/swap.
+
+Manual worker startup (non-Docker production)
+- If you are not yet running production in Docker, start the worker using the restart wrapper script:
+
+  ```sh
+  source .venv/bin/activate
+  DJANGO_SETTINGS_MODULE=rad.settings ./scripts/run-db-worker.sh
+  ```
+
+- This script restarts `db_worker` if it exits unexpectedly.
+
+- To run it in the background and keep logs:
+
+  ```sh
+  nohup DJANGO_SETTINGS_MODULE=rad.settings ./scripts/run-db-worker.sh > logs/db_worker.log 2>&1 &
+  ```
+
+- To verify it is still running:
+
+  ```sh
+  ps aux | grep "manage.py db_worker" | grep -v grep
+  tail -f logs/db_worker.log
+  ```
+
 - By default the development nginx ports are set in `.env.dev` to avoid colliding with a host nginx. The defaults now are:
   - `NGINX_HTTP_PORT=8080`
   - `NGINX_HTTPS_PORT=8444`