Groups act as visual organizers in the sites table. Monitors can be
assigned to a parent group via the form. Group rows show aggregated
worst-child status, children render with tree chars (├/└), and Space
toggles collapse/expand. Group form hides irrelevant connection and
advanced sections.
Prevent accidental deletes with y/n confirmation dialog. Validate all
numeric form inputs (interval, port, timeout, threshold, retries) with
range checks instead of silently defaulting to zero. Escape user-supplied
data in status page JavaScript to close XSS via monitor names. Persist
check history to new check_history table so sparklines and uptime
percentages survive restarts.
lerko