Mörsergranate: impact marker on the ground until the explosion

The landing point is noted from the grenade's cEventFX 0x96 at launch; a
translucent red circle with the explosion radius (shared ImpactRadius) is
drawn after the world's ground, under the objects, and ends when that
grenade's impact gathers its targets. Ground -> screen projection in
game/engine/worldview.h.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tools/names.txt

@@ -437,3 +437,6 @@
 0x006336b0 World_VisitedBorderCell           # thiscall (cx, cy), ret 8: border byte, 0 outside 100x100
 0x006c8580 cUI_Megamap::DrawVisitedBorder    # thiscall (device), ret 4: 2x2 px red (0xffff0000) dot per border bit, +-10/+-20 px from the sector origin
 0x006c87c0 cUI_Megamap::DrawQuestMarkers     # thiscall (device), ret 4: quest book entries (0xaaaf00)
+0x00622700 WorldToPlane                      # cdecl (out vec3, in vec3), plain ret: world units -> world pixels (iso matrix 0xad5710)
+0x0062d530 cWorldView0::DrawGroundQuads      # thiscall (renderer), ret 4: the ground, before the objects
+0x0041e0a0 cEventFX::Construct               # thiscall (code, owner, target, position 4 dwords, ...), ret 0x44