SudTask.on_step_changed() set the controller's target temp/rate on
every step, but never touched the real Pot's or the Smith predictor's
internal model's thermal mass (M/C) - those stayed frozen at
brewpi.py's startup DEFAULT_PLANT_PARAMS for the whole brew, even
though grain_mass/water_mass change per step (malt going in, water
boiling off) and demo_sud.py already recomputes them every step via
derive_plant_params(). Production SudTask just never got the same
treatment.
Adds SudTask.apply_plant_params(), called alongside the existing
theta_soll/heatrate_soll push, mirroring the demo. Needs the real Pot
now, so SudTask takes a `pot` constructor arg; set_model_params() is
only called if the configured controller actually defines one (the
"Normal" pid_type doesn't).
jens
e171892804