8 independent charts, each a separate MiniChart in streaming mode. On every tick each tile calls
chart.push(value, epochSec, seriesIdx) — an O(1)-per-point incremental render whose cost tracks canvas
width × series count, not how many samples have arrived. The X window scrolls via a per-pixel-column ring
(rangeSec = 60s) and memory is bounded by maxSamples. The Network I/O tile pushes
two series. Press Space to pause, or trim the cap to watch eviction shrink samples held.