fix: v3.0.0 -- thresholds on the free-fraction scale the assembly actually uses

Disassembling Cosmoteer.dll (tools/ildump.py) shows PartThresholdToggle
compares plain floats with no percent logic, and that a
NetworkResourceInput's Value is the free fraction (0..1) of the connected
network. v2.1.0 compared that against 2000000, so it always vented.

Thresholds are now 5% / 10% free as local constants. New guard
test_threshold_amounts_match_value_scale fails on the old values. README
corrects the earlier wrong diagnosis of v2.0.0.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011oLWY1G6S8U35bi2FxVWni

components/radiator_auto.rules

@@ -18,41 +18,41 @@
 
 // --- Is the heat network running out of room? -------------------------------
 //
-// Measured locally, exactly the way the heat exchanger decides whether it can
-// still push heat into the network (heat_exchanger.rules: IsNetworkHeatNonFull
-// reads a bare NetworkResourceInput). A NetworkResourceInput's value is how much
-// the network can still accept.
+// Measured locally with a bare NetworkResourceInput, the same component an
+// overclocked part pushes its heat through (base_part_overclock.rules:
+// NetworkHeatInput), so this is exactly the producer's view of the network.
 //
-// Reading a thermal battery's own HeatStorage does NOT work for this. That
-// storage is wrapped by a NetworkResourceStore, and v2.0.0 held heat forever --
-// batteries visibly full, parts cooking -- because a local percentage threshold
-// on it never crossed. This measures the network itself instead, from the part
-// that acts on the answer, so no cross-part broadcast is involved at all.
-//
-// Amounts are resource units: 1 status heat = 1000 resource units
-// (statuses/heat/heat.rules: STATUS_TO_RESOURCE_RATIO).
+// Its Value, from Cosmoteer.dll (PartNetworkResourceInput.get_Value, see
+// tools/ildump.py), is the FREE FRACTION of the connected heat storage:
+//   1 - stored / total capacity   -> 1.0 empty, 0.0 full, 0 if nothing attached
+// and a ThresholdToggle compares that against MinAmount/MaxAmount as plain
+// floats, so the amounts below are fractions too ("5%" is 0.05).
 
 AutoRad_NetworkSpace
 {
 	Type = NetworkResourceInput
 	ResourceType = heat
 	Mode = DistributeProportionallyByAvailable
+	Categories = [ thermal_storage ]
 }
 
-// Under ~2000 status heat of headroom left: vent.
+// Vent while less than VENT_BELOW_FREE of the network is still free.
 AutoRad_SpaceLow
 {
 	Type = ThresholdToggle
 	ValueFrom = AutoRad_NetworkSpace
-	MaxAmount = 2000000
+	VENT_BELOW_FREE = 5%
+	MaxAmount = &VENT_BELOW_FREE
 }
 
-// Back above ~6000 status heat of headroom: safe to bank heat again.
+// Hold heat again once at least HOLD_ABOVE_FREE is free. The gap between the
+// two is a deadband so radiators do not chatter at the threshold.
 AutoRad_SpaceAmple
 {
 	Type = ThresholdToggle
 	ValueFrom = AutoRad_NetworkSpace
-	MinAmount = 6000000
+	HOLD_ABOVE_FREE = 10%
+	MinAmount = &HOLD_ABOVE_FREE
 }
 
 AutoRad_LowTrigger