Combat: FIX missile direct damage 6x over-application -- damage once per salvo (task #62)

User live regression: missiles killed a mech in ~2 shots ("takes way more than 2
normally"). Root cause -- DamageZone::TakeDamage (arcade @0041e4e0 == WinTesla
DAMAGE.cpp:379) is `damageLevel += amount*scale` and IGNORES burstCount. So the
arcade's ONE cluster Missile per trigger lands its damageAmount EXACTLY ONCE; the
missileCount/burstCount split is cosmetic for zone damage (only gyro-bounce +
splash-falloff read burstCount). The port re-expresses that one cluster as N
flying rounds and was damaging on EVERY round = ~missileCount x too lethal on the
direct hit (mirrors the splash over-application fixed in 145a69f).

Fix (mislanch.cpp FireWeapon): only the salvo-LEAD round (i==0) carries damage
(damageData.damageAmount) AND the cluster splash; the other N-1 rounds are VISUAL
(damage 0) -- the tracer ripple, no extra damage. AC unaffected (one round/shot,
not a cluster).

Verified (BT_DMG_LOG [dmghit] trace): per-hit missile damage = clean 5.83, burst
1, once. Missiles-ONLY (BT_AF_MISSILE now independent of BT_AUTOFIRE), single
enemy, 45s: 8 damaging hits, top zone reaches only 0.18, NO death (was death in
~3 pulls) -- "way more than 2" restored. Earlier test deaths were BT_AUTOFIRE
firing laser+PPC+missiles combined, not missiles alone.

KB: combat-damage.md documents burstCount-ignored + the N-round cluster trap
(direct + splash both once-per-salvo).

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

game/reconstructed/mech4.cpp

@@ -3730,10 +3730,12 @@ void
 				LBE4ControlsManager::ButtonJoystickThumbLow,	// 0x46
 				LBE4ControlsManager::ButtonJoystickThumbHigh,	// 0x47
 			};
-			// DEV: BT_AF_MISSILE=1 also pulses the missile group (ThumbHigh) so a
-			// headless rig can exercise the launcher (splash verification, task #62).
+			// DEV: BT_AF_MISSILE=1 pulses the missile group (ThumbHigh).  INDEPENDENT
+			// of BT_AUTOFIRE (which drives the main gun group) so a headless rig can
+			// exercise MISSILES ONLY -- isolates missile damage/splash from laser+PPC
+			// fire (task #62 TTK verification).
 			static const int s_afMissile = getenv("BT_AF_MISSILE") ? 1 : 0;
-			const int autofireMsl = (s_afMissile && gBTDrive.fireForced && targetInArc) ? s_afPhase : 0;
+			const int autofireMsl = (s_afMissile && targetInArc) ? s_afPhase : 0;
 			int want[4];
 			want[0] = ((gBTLaserKey   && targetInArc) || autofire) ? 1 : 0;
 			want[1] = (gBTPinkyKey   && targetInArc) ? 1 : 0;	// key '4' (was unmapped)

game/reconstructed/mechdmg.cpp

@@ -424,7 +424,14 @@ void
 	}
 
 	// ---- real zone: apply to armour/structure ----
+	Scalar preLvl = damageLevel;
 	DamageZone::TakeDamage(damage);							// FUN_0041e4e0
+	if (getenv("BT_DMG_LOG"))
+		DEBUG_STREAM << "[dmghit] mech=" << mech->GetEntityID()
+			<< " zone=" << damageZoneIndex << " vital=" << (int)vitalDamageZone
+			<< " type=" << (int)damage.damageType << " amt=" << damage.damageAmount
+			<< " burst=" << damage.burstCount
+			<< " lvl " << preLvl << "->" << damageLevel << "\n" << std::flush;
 
 	Mech__DamageZone *parent = parentArtifactZone.GetCurrent();	// FUN_00417ab4(this+0x62)
 	if (parent != 0)

game/reconstructed/mislanch.cpp

@@ -305,15 +305,19 @@ void MissileLauncher::FireWeapon()
 	// on the authored up-tilt, then the seeker loft + steering arc it onto the target.
 	int nmiss = (missileCount > 0 && missileCount < 40) ? missileCount : 1;
 	for (int i = 0; i < nmiss; ++i)
-		// SPLASH (task #62 fix): the whole salvo re-expresses ONE arcade cluster
-		// missile, which does ONE SplashDamage event with baseBurst = the cluster
-		// count.  Tag ONLY the first round as the salvo lead (splash_burst = nmiss);
-		// the rest carry 0 so splash fires once per salvo, not once per visual round
-		// (which floored-at-1 N times = ~missileCount-x over-splash).
-		BTPushProjectile(muzzle, o, target, targetPos, speed, damageData.damageAmount,
+		// DAMAGE + SPLASH ONCE PER SALVO (task #62 fix): the arcade fires ONE
+		// cluster Missile per trigger, and its zone damage is applied EXACTLY ONCE
+		// -- DamageZone::TakeDamage (@0041e4e0) is `damageLevel += amount*scale`
+		// and IGNORES burstCount.  The port draws that cluster as N visual rounds;
+		// damaging on EVERY round applied the hit N times = ~missileCount-x too
+		// lethal (the "2-shot kill" regression).  Only the LEAD round (i==0)
+		// carries the missile's damageAmount + the cluster splash; the rest are
+		// VISUAL (damage 0) -- the ripple of tracers, no extra damage.
+		BTPushProjectile(muzzle, o, target, targetPos, speed,
+						 (i == 0) ? damageData.damageAmount : 0.0f,
 						 &launchVelocity, 1,
 						 subsystemID /*messmgr explosion bundling at impact (task #7)*/,
-						 (i == 0) ? nmiss : 0 /*salvo-lead cluster splash*/);
+						 (i == 0) ? nmiss : 0 /*salvo-lead: cluster splash baseBurst*/);
 
 	// Salvo replication (missile-visibility wave): bump the fire counter + stamp
 	// the aim point; the extended update record carries both to peer nodes.