fix: force heater/stirrer safe on SIGTERM, not just SIGINT

systemctl stop/restart send SIGTERM, whose default disposition kills
the process immediately - skipping the shutdown finally: block that
cancels tasks and forces both actors safe via their activate(False).
Route SIGTERM through the same KeyboardInterrupt path SIGINT already
uses, and add stirrer.activate(False) alongside the existing
heater.close() as a belt-and-suspenders fallback.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TvgC7oy9MxaA4ZQxXqkNdS

server/brewpi.py

@@ -3,6 +3,7 @@ import asyncio
 import functools
 import json
 import os
+import signal
 import sys
 import threading
 import time
@@ -202,23 +203,34 @@ if __name__ == '__main__':
 	threading.Thread(target=http_server.serve_forever, daemon=True).start()
 	print("Serving {} on http://0.0.0.0:{}".format(web_dir, args.http_port))
 
+	# systemd's `stop`/`restart` send SIGTERM, whose default disposition is to
+	# kill the process immediately - skipping the finally: block below
+	# entirely, leaving the heater/stirrer at whatever they were last set to.
+	# Routing it through the same KeyboardInterrupt path Ctrl-C (SIGINT)
+	# already uses gets it the same graceful, actor-safing shutdown.
+	signal.signal(signal.SIGTERM, signal.default_int_handler)
+
 	loop = asyncio.get_event_loop()
 	try:
 		loop.run_forever()
 	except KeyboardInterrupt:
 		print("\nShutting down...")
 	finally:
-		# Cancel all tasks so their finally blocks (e.g. HeaterTask's
-		# `with device.open()`) get a chance to run before we close the port.
+		# Cancel all tasks so their finally blocks (e.g. HeaterTask's/
+		# StirrerTask's `with device.open()`) get a chance to run before we
+		# close the port - this is what actually forces the heater to 0 W
+		# (AHeater.activate(False)) and the stirrer to a stopped state
+		# (AStirrer.activate(False)) on any exit that reaches here.
 		pending = asyncio.all_tasks(loop)
 		for task in pending:
 			task.cancel()
 		if pending:
 			loop.run_until_complete(asyncio.gather(*pending, return_exceptions=True))
 		server_log_task.write()
-		# Belt-and-suspenders: explicitly close the heater connection even if
-		# the task cleanup above failed to reach HeaterHendi.activate(False).
+		# Belt-and-suspenders: explicitly deactivate both actors even if the
+		# task cleanup above failed to reach their own activate(False).
 		heater.close()
+		stirrer.activate(False)
 		http_server.shutdown()
 		loop.close()
 		print("Server stopped.")