Audio: restore the dropped ExecuteWatchers poll -- polled audio watchers were ALL dead (task #50)

User: "when I start moving all the sounds fade away, no footsteps."  Diagnosis
chain (all empirical, BT_AUDIO_SPATIAL/BT_ATTRBIND_LOG traces):
- The audio head DOES track the mech (listener-relative positioning verified
  while driving) -- not a spatial bug.
- The idle sounds correctly STOP on leaving the standing state; the MOVING
  sounds never started because every POLLED audio watcher was dead:
  the reconstructed Mech::PerformAndWatch replaced the engine performance but
  dropped the ExecuteWatchers() step from the engine tail (Simulation::
  PerformAndWatch = Perform -> ExecuteWatchers -> WriteSimulationUpdate).
  Only PUSHED StateIndicator watchers (SetState->Execute) ever fired -- which
  is exactly why state sounds worked but footsteps/motion-scaled audio didn't.
  FIX: poll ExecuteWatchers() (AreWatchersDelayed-gated) before the update
  write.  Immediately unlocks the polled family: MissileLoaded01/LaserLoaded01
  ready dings, ProgramButton01, motion scales (PlayNote 15 -> 30 per run).

- FootStep (0x1e) backed REAL: was the inert attrPad (an AudioLogicalTrigger
  polls it -- threshold-crossing pulse per foot plant).  New footStep member,
  pulsed by SetBodyAnimation on entering any locomotion clip 1..0x17 (runtime
  stride alternation MEASURED as body states 12<->13 -- the enum-name numbering
  does not match runtime clip ids), decayed by IntegrateMotion (~1/3 s).
- Footstep volume is speed-scaled (AudioMotionScale on LocalVelocity): at
  standstill the transient start computes volume 0 and the renderer drops it
  (LowAudioVolumeThreshold) -- so footfalls are audible at real walking speed.

Diagnostics kept (BT_AUDIO_SPATIAL): spatial dist/vol per source, CLIPPED/DROP/
START at the request gate, vol=0 factor breakdown, scale->0 sends, trigger
notifications, watcher poll-rate probe.

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

game/reconstructed/mech4.cpp

@@ -292,6 +292,11 @@ Logical
 	// Choose this frame's forward-cycle slew rate.
 	forwardCycleRate = airborneSelect ? airborneCycleRate : groundCycleRate;	// 0x344<-0x5bc/0x5b8
 
+	// FootStep pulse decay (see SetBodyAnimation): clear the contact flag a few
+	// frames after the plant so the AudioLogicalTrigger re-arms for the next step.
+	if (footStepDecay > 0 && --footStepDecay == 0)
+		footStep = 0;
+
 	if (IsDisabled())								// FUN_0049fb54
 	{
 		ReconQuatIdentity(&angularAccum, &kIdentityQuat);		// was raw this+0x298 (stomped projectedVelocity)
@@ -5193,6 +5198,16 @@ void
 	// writer re-dispatches SetBodyAnimation on the WRITER -- the real-clock crash
 	// rode this path with legAnimationState still 0xCDCDCDCD).  Discard replicant
 	// marks instead.
+	// WATCHER POLL (engine Simulation::PerformAndWatch tail, SIMULATE.cpp:460):
+	// the engine path ends Perform() -> ExecuteWatchers() -> WriteSimulationUpdate().
+	// This reconstruction replaced the whole performance but DROPPED the
+	// ExecuteWatchers() step, so the entity-level POLLED audio watchers
+	// (AudioLogicalTrigger FootStep, AudioMotionScale/Trigger LocalVelocity, ...)
+	// never executed -- only the PUSHED StateIndicator watchers fired.  That's
+	// why footsteps/motion-scaled sounds were silent while state sounds worked.  [T0]
+	if (!AreWatchersDelayed())
+		ExecuteWatchers();
+
 	if (GetInstance() != ReplicantInstance)
 		WriteSimulationUpdate(update_stream);
 	else