Audio: in-game TRIGGERING works -- real StateIndicator attrs + audio-watcher databinding (task #50)

Enabling audio unlocked L4AudioRenderer::CreateEntityAudioObjects, which binds
AudioStateWatchers to entity/subsystem state attrs BY NAME (attribute-pointer
databinding) and calls AddAudioWatcher on them.  The reconstruction pointed the
Mech's state attrs at the scalar read-pad `attrPad` (fine for gauges that READ a
value, fatal for a state watcher that calls a METHOD) -> AV in SChainOf::Add on
0xCDCDCDCD.  Root-caused via cdb + a BT_ATTRBIND_LOG trace in AttributeWatcher.

Mech-level state audio now REAL + driven (verified: walking fires SetupPatch +
PlayNote/alSourcePlay, patches 78/80/116):
- AnimationState (0x1f) / ReplicantAnimationState (0x20): real StateIndicators
  (0x21 states covering MechAnimationState 0..0x20), driven from SetBodyAnimation
  so footstep/gait/transition sounds fire on animation change.
- CollisionState (0x16): real 4-state StateIndicator driven from ProcessCollision
  via collisionTemporaryState (the deferred @4aa741 per-frame zero + the
  part_012.c:15406-15413 contact tail, InitialHit accumulation; the 1-vs-2 Slide
  split awaits the 0x240/0x244 floats still stubbed by fieldAt()).
- @0x44c CORRECTED: "ammoState (0/1 leaking/2 dry)" was a mislabel -> it is
  collisionTemporaryState (never read as ammo).

Bring-up guards [T3, temporary, self-clearing] so audio-on is STABLE while the
subsystem state models are still stubs (Generators/Condensers/Myomers/Torso/
Avionics/Reservoir/ControlsMapper -- ~15 subsystems, ~40 attrs: GeneratorState,
CondenserState, ReportLeak, ...): a NULL subsystem attr redirects to an inert pad
(was a fatal Fail); an AudioStateWatcher on an unconstructed StateIndicator (null/
0xCDCDCDCD) skips instead of AV.  Both pass automatically once the subsystem is
reconstructed.  Those subsystem sounds stay silent until then (their audio wave).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

engine/MUNGA/AUDWTHR.cpp

@@ -1,3 +1,4 @@
+#include <cstdlib>
 #include "munga.h"
 #pragma hdrstop
 
@@ -873,6 +874,26 @@ AudioStateWatcher::AudioStateWatcher(
 	AudioWatcherOf<StateIndicator>(stream, entity)
 {
 	Check_Pointer(attributePointer);
+	// BRING-UP GUARD [T3, temporary]: an AudioStateWatcher binds to a StateIndicator
+	// attribute BY NAME.  The Mech's own state indicators (SimulationState, Animation/
+	// ReplicantAnimationState, CollisionState) are real; but audio also binds state
+	// attrs on subsystems that are not fully reconstructed yet (GeneratorState,
+	// CondenserState, Torso MotionState, ...).  Those resolve to an unconstructed
+	// object -- a null/garbage vtable at +0 or a debug-fill (0xCDCDCDCD) watcher chain
+	// at +0x18 -- and AddAudioWatcher would AV in SChainOf::Add.  Skip the register
+	// (that subsystem's state audio stays silent) until the subsystem is built; this
+	// is SELF-CLEARING (a real StateIndicator passes).  See docs: audio subsystem wave.
+	{
+		unsigned vt    = *(unsigned*)attributePointer;
+		unsigned chain = *(unsigned*)((char*)attributePointer + 0x18);
+		if (vt == 0 || vt == 0xCDCDCDCD || chain == 0xCDCDCDCD)
+		{
+			if (getenv("BT_AUDIO_LOG"))
+				DEBUG_STREAM << "[audiostate] skip watcher on unbuilt StateIndicator "
+					<< attributePointer << " (vt=" << (void*)vt << ")\n" << std::flush;
+			return;
+		}
+	}
    Cast_Object(StateIndicator*, attributePointer)->AddAudioWatcher(this);
 }