Fix BT_SPAWN_AT terrain embed + add BT_COOL_LOG probe

BT_SPAWN_AT teleport set only X/Z, keeping the old (dropzone) Y -- so teleporting to
a new spot embedded the mech in sloped terrain (user-reported).  Lift the teleport
+500 above the old elevation so the authentic per-frame ground SNAP (BoxTree
FindBoundingBoxUnder, no gravity) settles it onto the surface next frame (the snap
only lowers, so it must start above the surface).  Diagnostic only.

Also BT_COOL_LOG (heat.cpp): logs a heat subsystem's damageLevel/heatLoad/coolantDraw
when it carries damage -- for the 'do damaged mechs leak coolant' investigation.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

game/reconstructed/heat.cpp

@@ -818,6 +818,15 @@ void
 		coolantDraw = 0.0f;
 	}
 
+	// DIAG (BT_COOL_LOG): fire whenever THIS heat subsystem carries any damage --
+	// answers "does damaging a mech drain its coolant?".  Shows the damageLevel the
+	// leak reads (@0xE0), the heat load, the resulting draw, and the live level.
+	if (getenv("BT_COOL_LOG") && zoneDamage > 0.001f)
+		DEBUG_STREAM << "[cool] " << GetName() << " dmg=" << zoneDamage
+			<< " heatLoad=" << heatLoad << " draw=" << coolantDraw
+			<< " coolantLevel=" << coolantLevel << "/" << thermalCapacity
+			<< "\n" << std::flush;
+
 	Scalar amount = coolantDraw * time_slice;
 	if (coolantLevel < amount)
 	{

game/reconstructed/mech4.cpp

@@ -2376,6 +2376,13 @@ void
 				s_spawnAt = 2;
 				localOrigin.linearPosition.x = s_sx;
 				localOrigin.linearPosition.z = s_sz;
+				// FIX (user-reported: teleport embeds the mech in sloped terrain):
+				// BT_SPAWN_AT set only X/Z, keeping the OLD (dropzone) Y -- wrong for
+				// the new ground height.  Lift the mech WELL ABOVE local terrain so the
+				// authentic per-frame ground SNAP (BoxTree FindBoundingBoxUnder, no
+				// gravity) settles it onto the surface next frame.  The snap only
+				// lowers, so it must start above the surface, not below.
+				localOrigin.linearPosition.y += 500.0f;
 				if (s_haveH)
 				{
 					gDriveHeading = s_sh;