log: Sud lifecycle transitions and stirrer/heater connect state

Logs load/start/pause/continue/stop/entering-step/wait-user/finished
on Sud (components/sud.py) and connected/disconnected on
StirrerTask/HeaterTask, using the self.log added earlier.

SudForecastEstimator.estimate() (components/sud_forecast.py) drives its
own throwaway Sud through an entire schedule in a tight loop (no real
waiting) to predict its duration, and re-runs that on every real step
transition too - since it's still a Sud, it logged through the exact
same "Sud" logger as the real, server-driven one, making an instant
internal forecast run indistinguishable in the log from an actual
brew. Gave it its own "SudForecastEstimator" logger, silenced to
WARNING by default, so only the real Sud's transitions show up.

tasks/heater.py

@@ -33,6 +33,7 @@ class HeaterTask(ATask):
 		self._on_connected_changed = callback
 
 	def on_connected_changed(self, value):
+		self.log.info("Connected" if value else "Disconnected")
 		fire_and_forget(self.send({'Connected': value}))
 		if self._on_connected_changed:
 			self._on_connected_changed(value)

tasks/stirrer.py

@@ -33,6 +33,7 @@ class StirrerTask(ATask):
 		self._on_connected_changed = callback
 
 	def on_connected_changed(self, value):
+		self.log.info("Connected" if value else "Disconnected")
 		fire_and_forget(self.send({'Connected': value}))
 		if self._on_connected_changed:
 			self._on_connected_changed(value)