v2.1.0 — the trace chart menu-bar label

Added

• --label chart: the last 60 seconds, on the menu bar. The label slot could show a number or
  a fixed tag, but a single reading can't tell you whether a spike is just starting or already over,
  and the dropdown's sparkline only showed that after a click. A new label mode, Trace Chart
  (--label chart, CO_AWARENESS_LABEL=chart, or Settings ▸ Menu Bar Label), draws the active
  source's load history as a 45 pt bar sparkline in the adjacent slot. It uses the same
  green/amber/red thresholds as the dropdown (inverted for battery) and redraws on the same 2 s tick.
  The slot keeps a fixed width, so nothing beside it moves; a Keep Awake countdown sits next to the
  chart, closest to the icon, in the Keep Awake tint. Remembered across relaunches like the other modes.
  chart is now a reserved keyword, so a custom label reading literally "chart" can't be expressed.