[Bug / Feature Request]: negative temperatures in chart

[pixelpieper]

I am using a Duet board as a temperature controller for a measurement setup, using a peltier element for subzero temperatures. Unfortunately the temperature chart in DWC doesn't scale down to negative temperatures right now:

My proposal would be to extend the lowest temperature down to either

min(0, min(active_tooltemp_list),min(active_bedtemp_list),min(active_chambertemp_list))

or

min(0, active_tool_temperature,active_bed_temperature, active_chamber_tamperature)

This keeps the behavior as is for normal users while extending the chart down if required.

[oliof]

@pixelpieper maybe check the BtnCmd plugin for a customized UI and temp chart