Remove the unused tc_trace logging

trace_tc (tasks/tracer.py's TracerTask wired to a generic Tracer instance)
was logging to tc_trace.mat, but its var_list was empty, so it only ever
wrote a bare tick counter - no actual tc data, despite the name. Drop the
dead plumbing and the now-unused tracer.py module entirely; the real,
populated brewpi.mat logging (sensor/heater/tc data, built directly inside
TracerTask) is untouched.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DkkuG48uHFCGKe6dPSERFk

tasks/tracer.py

@@ -5,7 +5,6 @@ from ws.message import MsgIo
 from components import ATemperatureSensor
 from components import AHeater
 from components import APid
-from tracer import Tracer
 
 import numpy as np
 import scipy.io
@@ -13,7 +12,7 @@ import os
 
 
 class TracerTask(ATask):
-	def __init__(self, sensor: ATemperatureSensor, heater: AHeater, temp_ctrl: APid, tracer: Tracer, interval, msg_handler: MsgIo, path= './logs'):
+	def __init__(self, sensor: ATemperatureSensor, heater: AHeater, temp_ctrl: APid, interval, msg_handler: MsgIo, path= './logs'):
 		ATask.__init__(self, interval)
 		if not os.path.exists(path):
 			os.makedirs(path)
@@ -24,7 +23,6 @@ class TracerTask(ATask):
 		self.sensor = sensor
 		self.heater = heater
 		self.temp_ctrl = temp_ctrl
-		self.tracer = tracer
 		self.path = path
 
 	async def recv(self, data):
@@ -51,8 +49,6 @@ class TracerTask(ATask):
 		filename_full = os.path.join(self.path, '') + name + "." + time.strftime("%Y%m%d%H%M%S", time.localtime()) + ".mat"
 
 		while True:
-			self.tracer.process()
-
 			_timestamp = np.append(_timestamp, timestamp)
 			_sensor_temp = np.append(_sensor_temp, self.sensor.temperature())
 			_heater_power = np.append(_heater_power, self.heater.get_power())