Build the heater/pot/sensor rig as one unit, picked by plant_name alone

heater_name/sensor_name/plant_name were three independent config keys,
each picked via its own factory - in practice sim and real hardware
are never actually mixed and matched, so this could (nonsensically)
disagree, e.g. a real heater paired with a simulated sensor.

Add PlantFactory (components/plant/plant_factory.py): plant_name alone
now builds the whole rig together. "sim" gets HeaterSim/Pot (the
modeled plant, as before)/TempSensorSim. Anything else gets
HeaterHendi/PotReal/TempSensor_max31865 - PotReal is a new, deliberately
unmodeled Pot for the real, physical kettle (components/plant/pot_real.py):
the real temperature comes straight from the real sensor, not from a
model, so it just accepts and ignores set_plant_params()/
set_ambient_temperature()/initial() and reports no temperature of its
own, satisfying PotTask/SudTask's interface with nothing to actually
simulate.

heater_name/sensor_name are gone from config.json.templ; server/brewpi.py
delegates to HeaterFactory/TempSensorFactory lazily from inside
PlantFactory, same as before, so real hardware's spidev/pyserial deps
still aren't needed just to import the module.

server/brewpi.py

@@ -7,10 +7,9 @@ import time
 from utils import ChangedFloat
 from ws.message import MessageDispatcher
 from ws.server.ws_server_multi_user import WsServerMultiUser
-from components.sensor import TempSensorFactory
 from components.pid import PidFactory
-from components.plant import Pot
-from components.actor import HeaterFactory, StirrerFactory
+from components.plant import PlantFactory
+from components.actor import StirrerFactory
 from components.sud import Sud
 from components.sud_forecast import SudForecastEstimator
 from tasks import TaskManager, TempSensorTask, HeaterTask, PotTask, TcTask, StirrerTask, SudTask, SudLogTask
@@ -64,24 +63,29 @@ if __name__ == '__main__':
 	# several schedules onto it later (see components/sud.py's Sud).
 	sud = Sud()
 
-	# Sensor
-	sensor = TempSensorFactory.create(config['Controller']['sensor_name'], temp_offset=-0.15, variance=0.01)
+	# Heater/Pot/Sensor - built together as one consistent rig by a single
+	# Controller.plant_name, rather than three independently-named
+	# components that in practice are never actually mixed and matched
+	# (see components/plant/plant_factory.py): "sim" gets HeaterSim/Pot
+	# (the modeled plant)/TempSensorSim; anything else gets HeaterHendi/
+	# PotReal (no model - the real kettle does its own physics)/
+	# TempSensor_max31865.
+	heater, pot, sensor = PlantFactory.create(config['Controller']['plant_name'], DT, config['Heater'])
+
 	sensor_task = TempSensorTask(sensor, DT_TASK, dispatcher.msgio_get("Sensor"))
 	taskmgr.add(sensor_task)
 
-	# Plant - seeded with the not-yet-loaded sud's own (now physically
-	# sane, see Sud.EMPTY_SUD) plant params right away, same as ambient
-	# below, so the simulated Pot already runs - manual heater
-	# power/Sud disabled or not - instead of sitting inert until a real
-	# Sud loads. A real Sud's own doc still overrides these the moment
-	# one is loaded (see tasks/sud.py's SudTask.apply_plant_params()).
-	pot = Pot(DT)
+	# Pot - seeded with the not-yet-loaded sud's own (now physically sane,
+	# see Sud.EMPTY_SUD) plant params right away, same as ambient below, so
+	# a simulated Pot already runs - manual heater power/Sud disabled or
+	# not - instead of sitting inert until a real Sud loads (PotReal just
+	# ignores this - see there). A real Sud's own doc still overrides
+	# these the moment one is loaded (see tasks/sud.py's SudTask.
+	# apply_plant_params()).
 	pot.set_ambient_temperature(theta_amb)
 	pot.set_plant_params(sud.derive_plant_params(sud.grain_mass, sud.water_mass))
 	taskmgr.add(PotTask(pot, DT_TASK, dispatcher.msgio_get("Pot")))
 
-	# Heater
-	heater = HeaterFactory.create(config['Controller']['heater_name'], config['Heater'])
 	heater.set_on_changed("power_eff", ChangedFloat(pot.set_power, prec=0).set)
 	heater_task = HeaterTask(heater, DT_TASK, dispatcher.msgio_get("Heater"))
 	taskmgr.add(heater_task)
@@ -128,8 +132,9 @@ if __name__ == '__main__':
 	if hasattr(tc, "set_model_power"):
 		heater.set_on_changed("power_set", tc.set_model_power)
 
-	# For simulation
-	if "sim" in config['Controller']['sensor_name']:
+	# For simulation - the sim sensor has no real plant to read, so it
+	# just reports back whatever the modeled Pot's own temperature is.
+	if plant_sim:
 		pot.set_on_changed("temp", ChangedFloat(sensor.set_fake_temp, prec=3).set)
 		sensor.set_fake_temp(pot.temp)