Create useBeszelSystemsSubscription and useBeszelFilteredSystems hooks
to eliminate duplicated subscription + cache-update + filtering logic
across grid/table/alerts. Add BeszelAreaChart wrapper and chart data
hooks (useSystemChartData, useDockerChartData) to reduce ~90 lines of
repetitive useMemo transforms in system-stats. Add portal tooltip with
mousemove listener gated on active state to prevent unnecessary
re-renders during drag-and-drop.
Thomas Camlong
3131687229