Clean up after Smith predictor rewrite and drop unused/stale config

[brewpi] - drop trace vars for the dtheta_ist_* attributes removed
when temp_controller_smith.py dropped Kalman filtering
[Pot] - drop unused kn field (never read since the noise-injection
code that used it was dropped)
[GUI] - default WS connection to ws://localhost:8765

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

brewpi/brewpi.py

@@ -51,14 +51,7 @@ if __name__ == '__main__':
 	tc_task = TcTask(tc, DT_TASK, dispatcher.msgio_get("TempCtrl"))
 	taskmgr.add(tc_task)
 
-	tc_trace_vars = [
+	tc_trace_vars = []
-		{'variable': 'theta_ist_plant', 'name': 'theta_ist_plant', 'unit': ''},
-		{'variable': 'dtheta_ist_plant', 'name': 'dtheta_ist_plant', 'unit': ''},
-		{'variable': 'theta_ist_model', 'name': 'theta_ist_model', 'unit': ''},
-		{'variable': 'dtheta_ist_model', 'name': 'dtheta_ist_model', 'unit': ''},
-		{'variable': 'theta_ist_model_delay', 'name': 'theta_ist_model_delay', 'unit': ''},
-		{'variable': 'dtheta_ist_model_delay', 'name': 'dtheta_ist_model_delay', 'unit': ''}
-	]
 
 	trace_tc = Tracer(tc, tc_trace_vars, name='tc_trace')
 

client/main_window.py

@@ -1272,7 +1272,7 @@ class Ui_MainWindow(object):
         self.label_5.setText(_translate("MainWindow", "Power [W]"))
         self.label_7.setText(_translate("MainWindow", "State"))
         self.label_state.setText(_translate("MainWindow", "State"))
-        self.plainTextUri.setPlainText(_translate("MainWindow", "ws://brewpi:8765"))
+        self.plainTextUri.setPlainText(_translate("MainWindow", "ws://localhost:8765"))
         self.label_8.setText(_translate("MainWindow", "Host"))
         self.menu_File.setTitle(_translate("MainWindow", "&File"))
         self.menu_Help.setTitle(_translate("MainWindow", "&Help"))

components/plant/pot.py

@@ -27,9 +27,6 @@ class Pot(APlant):
 		# Energy transport propagation delay
 		self.Td = params['Td']
 
-		# TBD
-		self.kn = params['kn']
-
 		# Plant temperature [°C]
 		self.temp = params['theta']