Fix issue in creature.cpp adding skull to master on summon AoE attacks

[jromap7]

• I have followed [proper The Forgotten Server code styling]code.
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Changes Proposed

Added code to ensure that when a player's summon damages another player with an AoE attack, the master player is correctly assigned a skull.

Code added:

if (attacker->getMaster() && attacker->getMaster()->getPlayer()) {
	Player* masterPlayer = attacker->getMaster()->getPlayer();
	masterPlayer->onAttackedCreature(this);
}

Issues Addressed

Fixes the bug where a player's summon (e.g., fire devil or fire elemental) using AoE spells did not assign a skull to the master player when damaging other players.

How to Test

1. Summon a creature (e.g., fire devil or fire elemental) as a player.
2. Have the summon cast an AoE spell near another player. You can summon 2 Fire Devils and make one attack the other.
3. Verify that the master player receives a skull when the AoE damages the other player.