Add sensor variance config and smooth heat-rate estimate

[Sensor] - replace TempSensorSim's hardcoded k_noise with configurable
temp_offset/variance, accept **kwargs on Max31865 too so both sensors
share a constructor signature usable from TempSensorFactory.create()
[Temp Controller] - low-pass filter the backward-difference heat-rate
estimate (alpha=0.1) in both temp_controller.py and
temp_controller_smith.py instead of using the raw, noisy derivative
[Pot] - drop kn from demo_pot.py's params, matching the unused-field
removal already made to pot.py itself

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/pid/temp_controller.py

@@ -7,11 +7,14 @@ class TempController(TempControllerBase):
 		self.dt = dt
 		self.last_theta_ist = 20
 		self.heatrate_ist = 0
+
 	def process(self):
 		# Process Kalman
 		self.theta_ist = self.theta_ist_set
 		heatrate = (self.theta_ist - self.last_theta_ist)/self.dt*60
-		self.heatrate_ist = heatrate
+
+		alpha = 0.1
+		self.heatrate_ist = (1-alpha) * self.heatrate_ist + alpha*heatrate
 		self.last_theta_ist = self.theta_ist
 
 		# Compensate for max heat rate to reduce overshoot

components/pid/temp_controller_smith.py

@@ -45,7 +45,9 @@ class TempController(TempControllerBase):
 		self.theta_ist = self.theta_ist_model + (self.theta_ist_plant - self.theta_ist_model_delay)
 
 		heatrate = (self.theta_ist - self.last_theta_ist)/self.dt*60
-		self.heatrate_ist = heatrate
+
+		alpha = 0.1
+		self.heatrate_ist = (1-alpha) * self.heatrate_ist + alpha*heatrate
 		self.last_theta_ist = self.theta_ist
 
 		# Compensate for max heat rate to reduce overshoot

components/sensor/tempSensorSim.py

@@ -6,13 +6,14 @@ class TempSensorSim(ATemperatureSensor):
 	def name(self):
 		return "FakeTemp"
 
-	def __init__(self, *args, **kwargs):
+	def __init__(self, temp_offset=0.0, variance=0.0, **kwargs):
 		ATemperatureSensor.__init__(self)
 		self.temp_set = 19.99
-		self.k_noise = 0.01
+		self.offset = temp_offset
+		self.variance = variance
 
 	def set_fake_temp(self, temp):
 		self.temp_set = temp
 
 	def temperature(self):
-		return self.temp_set + self.k_noise * np.random.normal(0, 1) / np.sqrt(12.0)
+		return self.temp_set + self.offset+ self.variance * np.random.normal(0, 1) / np.sqrt(12.0)

components/sensor/tempSensor_max31865.py

@@ -8,7 +8,7 @@ class TempSensor_max31865(ATemperatureSensor):
 	def name(self):
 		return "Max31865"
 
-	def __init__(self, temp_offset=0):
+	def __init__(self, temp_offset=0, **kwargs):
 		ATemperatureSensor.__init__(self)
 		# Open SPI bus
 		self.spi = spidev.SpiDev()