feat: make the radiator report its own internal state

v1.1.0 loaded cleanly and still did nothing, so the NetworkValue rewrite
was not the whole story. Rather than keep guessing at which link in the
chain is dead, add indicator icons bound to the internal signals.

An indicator draws while its toggle is off, so one glance at a radiator
now separates the cases that were previously indistinguishable:

  wrench absent   -> the AddBase never merged; nothing in the mod runs
  thermal missile -> no thermal-ammo signal arriving
  resource        -> no hold signal arriving from a battery

Tests check that every added indicator binds to a component that exists
and to a sprite that exists in the indicators atlas.

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

components/radiator_auto.rules

@@ -83,3 +83,14 @@ AutoPowerToggle
 	Toggles = [ PowerToggle, AutoRad_VentAllowed ]
 	Mode = All
 }
+
+// Diagnostic anchor. An indicator icon shows while its toggle is OFF, so an
+// icon bound to this one is visible whenever these components were merged onto
+// the part at all. If that icon is absent, the AddBase in mod.rules did not
+// take effect and nothing else in this file is running either -- which is the
+// single most useful thing to be able to tell apart from a dead signal.
+AutoRad_AlwaysOff
+{
+	Type = StaticToggle
+	ToggleOn = false
+}