proantitab: allow lp/luckperms in global; deny essentials.motd default

Defensive belt-and-suspenders for "no /help hint on join":
1. motd.txt already emptied (commit 7e7d18e)
2. LP: 'lp group default permission set essentials.motd false' applied
   live (h2 db updated at 18:35). Default group can no longer trigger
   on-join motd even if motd.txt gets refilled later.

ProAntiTab storage.yml: add lp + luckperms to global allow-list so the
deny-perm command itself can run via rcon (whitelist mode was blocking).

Note: LP h2 storage isn't tracked in repo (.empty-103450 placeholder
files only). Live server is source of truth for LP state.

live-server/plugins/ProAntiTab/storage.yml

@@ -6,6 +6,8 @@ global:
     - gamerule announceAdvancements
     - gamerule announceAdvancements false
     - gamerule keepInventory
+    - lp
+    - luckperms
     - execute
     - execute in
     - execute in minecraft:overworld