Fix HOLD<->COOL chattering caused by too-tight HoldCool threshold

HoldCool=0.1 was inherited from the pre-COOL-state era, where it meant
"eagerly give up active holding and coast" - harmless, since coasting
had no side effects. COOL is a real, actively-controlled state now
(its own pid_cool, reset on every entry), so a threshold this tight
relative to a real heater's discrete power steps (or even just sensor
noise) caused the system to flip in and out of COOL nearly every tick
once resting near a setpoint - resetting both pid_hold's and
pid_cool's integrators each time and never letting either actually
converge.

Confirmed via a full multi-task simulation (real Pot/Sensor/Heater/
TempCtrl tasks, not a simplified loop) of sude/sud_0010.json: 44+
TempCtrl state changes and the run not settling within hours at
HoldCool=0.1, dropping to 8 state changes and a clean 186.5 min finish
at HoldCool=1.0 (matching the other thresholds). This was the dominant
cause of real brews taking far longer than their nominal schedule
duration - not just a forecasting inaccuracy, an actual control-
quality bug.

components/pid/temp_controller_base.py

@@ -4,7 +4,14 @@ import enum
 
 DEFAULT_THRESHOLDS = {
 	"HoldHeat": 1.0,
-	"HoldCool": 0.1,
+	# HoldCool used to be 0.1 ("eagerly give up and coast" made sense back
+	# when COOL meant nothing more than going idle - it's an active state
+	# with its own PID now, so a threshold this tight relative to a real
+	# heater's discrete power steps/sensor noise causes the system to
+	# chatter in and out of it every tick, resetting both pid_hold's and
+	# pid_cool's integrators each time and never letting either actually
+	# converge. Symmetric with the others instead.
+	"HoldCool": 1.0,
 	"HeatHold": 1.0,
 	"HeatCool": 1.0,
 	"CoolHold": 1.0,

config.json.templ

@@ -30,7 +30,7 @@
 		},
 		"Thresholds": {
 			"HoldHeat": 1.0,
-			"HoldCool": 0.1,
+			"HoldCool": 1.0,
 			"HeatHold": 1.0,
 			"HeatCool": 1.0,
 			"CoolHold": 1.0,