Audio Phase 4c (AUDIO_FIDELITY F17/F19): impact scaling + the authored footstep feed

F17 CollisionSpeed (binary id 24 @0x4B4): real member captured as
|worldLinearVelocity| when the contact accumulator arms (0->1) -- the authored
AttackVolume [0.9,1] / Brightness [0.7,1] scales over impact speed [0,25] now
make harder hits sound louder and brighter.  ReduceButton (id 46 @0x340): real
watchable member (the keyboard rig never presses it).  UnstablePercentage
stays deferred: its sway/overspeed model @0x3F0 is the known gyro-ledger gap
(live writer unexported); binding without the model would be a stand-in.

F19 footstep feed (the invention is dead, long live the authored chain):
new [motionscalecfg/motiontrigcfg] traces recovered the authored configs --
EVERY motion watcher extracts |linearMotion| (motionValue=3); the footstep
volume mixer is fed by LocalAcceleration [0,10] -> ctl100 (per-stride kick)
+ LocalVelocity [0,0.6] -> ctl101 (0.4 base while moving).  The port never
wrote Mover::localAcceleration, so ctl100 read 0 and the old mech2.cpp
step-intensity broadcast (patch-sniffing, invented curve) fought the live
authored scale.  Now: localAcceleration.linear = d(published velocity)/dt --
EXACTLY the binary's derivation ((avgVel - prev)/avgDt into +0x1e4,
part_012.c:15186-15195) -- and the broadcast is REMOVED.

Regression (30s, walk throttle): stable; footfalls deliver through the
wholly-authored chain with per-stride VARYING gains (0.61/0.72/0.62 -- real
step dynamics, impossible under the old constant-curve invention).

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

engine/MUNGA/AUDWTHR.cpp

@@ -135,6 +135,12 @@ AudioMotionTrigger::AudioMotionTrigger(
 	MemoryStream_Read(stream, &motionType);
 	MemoryStream_Read(stream, &motionValue);
 
+	if (getenv("BT_ATTRBIND_LOG")) { static int s_mt=0; if (s_mt++<40)
+		DEBUG_STREAM << "[motiontrigcfg] attrPtr=" << (void*)attributePointer
+			<< " motionType=" << (int)motionType << " (0=linear,1=angular)"
+			<< " motionValue=" << (int)motionValue << " (0=X,1=Y,2=Z,3=len)"
+			<< "\n" << std::flush; }
+
 	PrimeWatcher();
 }
 
@@ -284,6 +290,12 @@ AudioMotionScale::AudioMotionScale(
 	MemoryStream_Read(stream, &motionType);
 	MemoryStream_Read(stream, &motionValue);
 
+	if (getenv("BT_ATTRBIND_LOG")) { static int s_ms=0; if (s_ms++<40)
+		DEBUG_STREAM << "[motionscalecfg] attrPtr=" << (void*)attributePointer
+			<< " motionType=" << (int)motionType << " (0=linear,1=angular)"
+			<< " motionValue=" << (int)motionValue << " (0=X,1=Y,2=Z,3=len)"
+			<< "\n" << std::flush; }
+
 	PrimeWatcher();
 }