feat(skills): end a dead caster's skill when a client reports it (CasterDead)

When a client gets EchoStartSkill (or SyncSkill) from a caster it sees
as dead, aimed at another object, it logs "msgEchoStartSkill
msgCasterDead" and sends CasterDead (120: optional i64Caster, optional
uiSkillHandle) through that target
(LWOSkillComponent::msgEchoStartSkill 0x00d5dc90). 303 live packets, the
target nearly always the attacked player, the caster a spawned enemy;
the next messages were mostly Die and SetStunned for the player. DLU
dropped it.

The server now ends that skill on the caster: its behaviors with that
handle are dropped (end entries run, pending timers and syncs discarded,
its projectiles removed), so a hit an enemy scheduled before dying does
not land later. It only does so when the server also sees the caster as
dead, so a client can't cancel a living enemy's attack. What live did
with the message is inferred from the name and when it was sent.

Check in game: kill an enemy in the middle of a slow or charged attack
(e.g. a Maelstrom horseman or a spider queen add): its attack does not
hit after it has died, and other enemies' attacks still hit normally.

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

dGame/dComponents/SkillComponent.h

@@ -88,6 +88,18 @@ public:
 	 */
 	void Interrupt();
 
+	/**
+	 * Ends a skill this entity is running: drops its behaviors (and their pending hits and projectiles) with that
+	 * skill handle
+	 * @param skillUid the skill handle
+	 */
+	void EndSkill(uint32_t skillUid);
+
+	/**
+	 * @return whether this entity runs a skill with that handle
+	 */
+	bool HasSkill(uint32_t skillUid) const { return m_managedBehaviors.contains(skillUid); }
+
 	/**
 	 * Starts a player skill. Should only be called when the server receives a start skill message from the client.
 	 * @param behaviorId the root behavior ID of the skill