Add mash-schedule (Sud) automation: temp/rate sequencing + stirrer switching

brewpi.py had a dead -m/--model CLI arg and sude/*.json schedules were
pure data with no code to drive them, despite the README documenting
them as if they were already wired up.

Add components/sud.py's Sud, which loads a sude/*.json schedule and
steps through its Rasten (ramp -> hold -> optional wait-for-user ->
next rest), and tasks/sud.py's SudTask, which drives the temperature
controller's theta_soll/heatrate_soll from the current rest and
switches the stirrer between continuous (ramping) and intermittent
(holding, via stirrSpeedRast/stirrDutyRast/stirrCycleTime) operation.
Exposes progress on a new "Sud" WebSocket channel and accepts
Start/Confirm commands. Enabled via a new optional top-level "sud"
config key (see config.json.templ/.sim).

"Reached target" is detected via abs(theta_ist - theta_soll_set) <
tolerance rather than tc.state == HOLD, since the latter can still
read HOLD left over from the previous rest for one tick after a new
target is pushed (tc.state only updates on the controller's own,
independently-scheduled process() tick).

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

tasks/__init__.py

@@ -5,3 +5,4 @@ from tasks.stirrer import *
 from tasks.pot import *
 from tasks.tempctrl import *
 from tasks.tracer import *
+from tasks.sud import *