Whirlwind respawn: authentic death->drop-zone->recreate cycle (task #52)

Death transition (mech4) now dispatches VehicleDead(-1) to the owning
player; BTPlayer::VehicleDeadMessageHandler restructured to the authentic
@004c05c4 three-way branch: -1 = death bookkeeping + sever playerVehicle
(wreck stays) + 5s re-post; >=0 = engine drop-zone hunt -> DropZoneReply
-> CreatePlayerVehicle (new mech); -2 = the acquire probe. Guarded on a
DropZones group so a zone-less mission stays dead instead of aborting.

Three latent bugs the respawn path exposed, all fixed:
- IsMechDestroyed latched on graphicAlarm>=9 alone; a later leg hit on the
  wreck rewrites the alarm to 4/3, un-latching -> the death transition
  re-ran (double kill/score, abort). Now latches on movementMode 2||9.
- Score handlers dereferenced the severed playerVehicle during the dead
  window; guarded.
- The console score flush routed a NetworkClient::Message through the
  player's Entity::Dispatch, which stamps entityID past the smaller struct
  -> /RTC1 stack overflow. Sent via application->SendMessage instead.
- Renderer LoadMission re-entry (per viewpoint-make) re-read the env INI;
  its light block Fail'd on stale sceneLightCount. Reset it in
  DPLReadEnvironment so the respawn's second read is clean.

Verified 2-node self-drive: B killed repeatedly by A respawns each time
(wreck stays), ticks + reloads + takes fresh damage on the new mech, no
abort/hang across multiple death->respawn cycles.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

game/reconstructed/mech4.cpp

@@ -141,6 +141,9 @@
 #include <BOXSOLID.hpp>		// BoxedSolid / BoxedSolidCollision / BoxedSolidCollisionList
 #include <cultural.hpp>		// CulturalIcon::IsStoppingCollisionVolume / GetClassDerivations
 #include <hostmgr.hpp>		// HostManager::GetEntityPointer (band-effect attacker resolve)
+#if !defined(PLAYER_HPP)
+#	include <player.hpp>	// Player::VehicleDeadMessage -- the death->respawn notification (task #52)
+#endif
 #if !defined(EMITTER_HPP)
 #	include <emitter.hpp>	// Emitter/PPC beam state (the per-weapon beam render walk)
 #endif
@@ -976,7 +979,20 @@ void
 Logical
 	Mech::IsMechDestroyed()
 {
-	// graphicAlarm level 9 = a vital zone / leg gone -> going down (mechdmg.cpp).
+	// AUTHENTIC LATCH first: IsDestroyed == (movementMode 2 || 9) -- the death
+	// modes (FUN_004ab1c8 zeroes locomotion for exactly these) [T1].  The death
+	// modes never revert, so a wreck STAYS destroyed.
+	//
+	// graphicAlarm >= 9 is only the vital-kill TRIGGER that enters the death
+	// transition (mechdmg.cpp:407/426).  It is a STATUS indicator, not a latch:
+	// a later leg hit on the wreck legitimately rewrites it to 4/3
+	// (mechdmg.cpp:417/419), which -- when this predicate was the alarm alone --
+	// "resurrected" the wreck (movementMode reverted to 1) and let the next
+	// vital hit run the WHOLE death transition again: double kill score, and a
+	// Score dispatched into the respawn window's severed playerVehicle -> the
+	// engine's Check(playerVehicle) abort (task #52 cdb catch).
+	if (movementMode == 2 || movementMode == 9)
+		return True;
 	return graphicAlarm.GetLevel() >= 9 ? True : False;
 }
 
@@ -1132,6 +1148,36 @@ void
 			<< " DESTROYED (death effects dispatched from the death transition) ***\n"
 			<< std::flush;
 	}
+
+	//
+	// --- RESPAWN CYCLE (task #52): notify the owning player of the death. ---
+	// The BTPlayer VehicleDead handler @004c05c4 receives this with
+	// deathCount == -1 (the ctor default = "immediate death notification"),
+	// does the death bookkeeping, severs playerVehicle (this wreck entity
+	// STAYS in the world) and re-posts the message to itself at +5 seconds
+	// (5.0f @004c0830) -> the engine drop-zone hunt -> DropZoneReply ->
+	// CreatePlayerVehicle (a NEW mech).  Only the owner pod's master has a
+	// live playerLink, which is exactly where the cycle must run; replicant
+	// wrecks just mirror the master's death.  [T1 the handler @004c05c4;
+	// T3 this dispatch site -- the binary's exact sender is undecoded, but
+	// the once-per-death transition is the only death edge and the message
+	// ctor's deathCount=-1 default exists for precisely this notification.]
+	//
+	{
+		Player *owner = GetPlayerLink();
+		if (owner != 0)
+		{
+			Player::VehicleDeadMessage
+				vehicle_dead(
+					Player::VehicleDeadMessageID,
+					sizeof(Player::VehicleDeadMessage)
+				);
+			owner->Dispatch(&vehicle_dead);
+			if (getenv("BT_DEATH_LOG"))
+				DEBUG_STREAM << "[death] VehicleDead(-1) dispatched to the owning player\n"
+					<< std::flush;
+		}
+	}
 }
 
 void