v0.3.16

Fixed

• Usage: active-minutes undercount — the idle-skip in daily
  downsampling compared all 28 ambient fields, but time-derived fields
  (window_remaining_minutes, window_resets_at) change every poll,
  preventing the skip from ever firing. Added activityKey() comparing
  only 4 traffic-indicator fields (concurrent_sessions,
  tokens_in, tokens_out, tokens_cached) so idle periods are
  correctly detected and excluded. Gap detection and degradation burden
  still use the full 28-field ambientKey (unchanged).
• Dashboard: heatmap brush reset on poll — the Recharts Brush
startIndex/endIndex were plain constants recomputed every render.
  When rows changed on each 60s poll, getDerivedStateFromProps
  reset the brush to full range. Converted to useState with a
  useEffect that resets only when the date preset changes.
• Dashboard: tooltip lag — TooltipProvider delay={300} caused a
  300ms open delay on all 63 tooltips. Changed to delay={0} (instant
  open) with closeDelay={150} to prevent flicker on rapid crossings.
• Dashboard: degradation bands extend past resolution —
  buildDegradationBands filtered out resolved events, causing bands
  to extend to lastTs instead of stopping at the resolution
  timestamp. Rewrote to walk all events (onset + morph + resolved):
  morph pushes the current band and re-anchors; resolved closes the
  band at the resolved timestamp; unresolved extends to lastTs.