Adds a left4me-workshop-refresh entry to the systemd-timers bundle,
firing nightly at 04:00 and invoking the new flask workshop-refresh
CLI that enqueues a refresh_workshop_items job. Owner of the job is
NULL (system-enqueued). The bw worker picks it up under existing
scheduler rules; idempotent against an already-queued/running refresh.
Also extends bundles/systemd-timers to accept an optional
environment_files key so the new unit can pull DATABASE_URL etc.
from /etc/left4me/{host,web}.env.