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

scripts/run-db-worker.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env sh
+set -eu
+
+ROOT_DIR="$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)"
+PYTHON_BIN="${PYTHON_BIN:-$ROOT_DIR/.venv/bin/python}"
+DJANGO_SETTINGS_MODULE="${DJANGO_SETTINGS_MODULE:-rad.settings}"
+RESTART_DELAY="${RESTART_DELAY:-3}"
+MAX_RESTARTS="${MAX_RESTARTS:-0}"
+
+if [ ! -x "$PYTHON_BIN" ]; then
+  echo "Python binary not found or not executable: $PYTHON_BIN" >&2
+  exit 1
+fi
+
+export DJANGO_SETTINGS_MODULE
+
+restart_count=0
+
+echo "Starting persistent db_worker loop"
+echo "Root: $ROOT_DIR"
+echo "Settings: $DJANGO_SETTINGS_MODULE"
+echo "Python: $PYTHON_BIN"
+
+while true; do
+  echo "[$(date -u +%Y-%m-%dT%H:%M:%SZ)] Launching db_worker"
+  "$PYTHON_BIN" "$ROOT_DIR/manage.py" db_worker
+  exit_code=$?
+
+  echo "[$(date -u +%Y-%m-%dT%H:%M:%SZ)] db_worker exited with code $exit_code"
+
+  if [ "$MAX_RESTARTS" -gt 0 ] && [ "$restart_count" -ge "$MAX_RESTARTS" ]; then
+    echo "Max restarts reached ($MAX_RESTARTS). Exiting." >&2
+    exit "$exit_code"
+  fi
+
+  restart_count=$((restart_count + 1))
+  echo "Restarting in ${RESTART_DELAY}s (restart #$restart_count)"
+  sleep "$RESTART_DELAY"
+done