fix: measure the network, not a battery's storage

v2.0.0 held heat forever: thermal batteries visibly full, parts taking
heat damage, radiators still idle. That is the dangerous direction.

The ceiling read a thermal battery's own HeatStorage with a percentage
threshold. That storage is wrapped by a NetworkResourceStore, and the
local read never crossed 98% however full the network actually got, so
the battery broadcast "hold" permanently.

Measure the network's remaining room directly instead, from the radiator
itself, with a bare NetworkResourceInput -- the same way the heat
exchanger decides whether it can still push heat. Vent below ~2000 status
heat of headroom, hold again above ~6000. Absolute headroom is also the
better metric: what matters is room against the generation rate, not a
percentage of whatever storage happens to be installed.

Polarity is now fail-safe. Holding requires positive evidence of
headroom, so anything missing or unmeasurable vents rather than holds --
the opposite of the failure above.

This deletes both broadcasters. The thermal battery and base_part_overclock
are no longer patched at all, and the mod touches two parts instead of
four. The launcher ammo signal stays; it is confirmed working in both
directions.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011oLWY1G6S8U35bi2FxVWni

tests/test_mod.py

@@ -443,7 +443,7 @@ def test_component_fields_exist_in_schema():
 #     the components existed on the parts, and every signal read zero.
 # ---------------------------------------------------------------------------
 
-NETWORK_COMPONENT_TYPES = {"NetworkValue", "NetworkValueReceiver"}
+NETWORK_COMPONENT_TYPES = {"NetworkValue", "NetworkValueReceiver", "NetworkResourceInput"}
 
 
 def collect_route_names(node, found=None):