feat: add missing force field, jetpack NPC and Skullkin volume scripts

Ported from the live server scripts that ship with the client:

- scripts\ai\LS\ForceFieldEffect.lua (LEGO Club and Starbase 3001 force
  fields): plays effect 3671 "cast" on whatever touches the phantom.
- scripts\ai\NP\L_NPC_NP_JETPACK_GUY.lua (jetpack ambient NPCs): plays
  the object's "launch" effect when used.
- scripts\02_server\Map\AM\L_SKELETON_SPAWNER_VOLUME.lua (Crux Prime
  Skullkin area): with 10 or more players in the volume the Skullkin
  engineer, miner and patroller networks maintain 2/6/6 instead of
  1/4/4, with a 60 second cooldown between changes and a catch-up check
  when it ends. Only players are counted, and the count never goes
  below zero.

WBL_Enemy_Grabbler.lua only sets wander variables for the old Lua
movement AI, so it joins the other alpha wander scripts in the excluded
list instead of logging as missing.

Refs #746

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dScripts/ai/GENERAL/ForceFieldEffect.cpp

@@ -0,0 +1,10 @@
+#include "ForceFieldEffect.h"
+
+#include "Entity.h"
+#include "GameMessages.h"
+
+void ForceFieldEffect::OnCollisionPhantom(Entity* self, Entity* target) {
+	if (!target) return;
+
+	GameMessages::SendPlayFXEffect(target, 3671, u"cast", "", LWOOBJID_EMPTY);
+}