fix(Scripts/ObsidianSanctum): Despawn drakes on Sartharion death (#25488)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/server/scripts/Northrend/ChamberOfAspects/ObsidianSanctum/boss_sartharion.cpp

@@ -411,6 +411,11 @@ struct boss_sartharion : public BossAI
     {
         _JustDied();
         Talk(SAY_SARTHARION_DEATH);
+
+        // Despawn remaining drakes
+        for (uint32 i : dragons)
+            if (Creature* boss = instance->GetCreature(i))
+                boss->DespawnOrUnsummon();
     }
 
     void SetData(uint32 type, uint32 data) override