Fix worker service and Docker storage permission issues (Issues #66, #67)

Issue #66: Remove redundant picpeak-workers.service creation from setup script.
Workers (fileWatcher, expirationChecker, emailProcessor) are now started
automatically by server.js, so a separate systemd service is not needed.
The legacy service cleanup code is retained for migration purposes.

Issue #67: Ensure storage directories exist at container startup in
wait-for-db.sh. When host directories are bind-mounted in Docker, the
container's built-in directories are overridden. This fix creates the
required directory structure (events/active, events/archived, thumbnails)
before the application starts, preventing EACCES permission errors.

backend/wait-for-db.sh

@@ -43,6 +43,13 @@ done
 
 >&2 echo "Target database \"$target_db\" is ready."
 
+# Ensure storage directories exist with proper permissions (Issue #67 fix)
+# When host directories are bind-mounted, the container's built-in directories are overridden
+# This ensures the required directory structure exists before the application starts
+echo "Ensuring storage directories exist..."
+STORAGE_BASE="${STORAGE_PATH:-/app/storage}"
+mkdir -p "$STORAGE_BASE/events/active" "$STORAGE_BASE/events/archived" "$STORAGE_BASE/thumbnails" 2>/dev/null || true
+
 # Run migrations (use safe runner in production)
 echo "Running database migrations..."
 if [ "$NODE_ENV" = "production" ]; then