Replace ntcharts with custom multi-row sparkline. Each bar is color-
coded by latency threshold (green < 200ms, yellow < 500ms, red > 500ms)
and DOWN checks render in red. 3 rows tall with 24 discrete levels.
Y-axis labels (max/min ms) on the left, Min/Avg/Max stats below.
Zero external dependencies — removed ntcharts.
lerko
4af800a359
