fix: Magic NPCs now use spell range (#1870)

### Summary
- Drastically streamlines the spell targeting by collapsing the target classes into a single `SpellTarget<T>` class.
- Moves TargetRange to the spell itself so it can be used by MageAI.
- Changes range check in MageAI to use TargetRange. This should fix target acquisition bugs

Projects/UOContent/Spells/Targeting/SpellTarget.cs

@@ -0,0 +1,58 @@
+using Server.Targeting;
+
+namespace Server.Spells;
+
+public class SpellTarget<T> : Target, ISpellTarget<T> where T : class, IPoint3D
+{
+    private static readonly bool _canTargetStatic = typeof(T).IsAssignableFrom(typeof(StaticTarget));
+    private static readonly bool _canTargetMobile = typeof(T).IsAssignableFrom(typeof(Mobile));
+    private static readonly bool _canTargetItem = typeof(T).IsAssignableFrom(typeof(Item));
+
+    private readonly bool _retryOnLos;
+    protected readonly ITargetingSpell<T> _spell;
+
+    public SpellTarget(
+        ITargetingSpell<T> spell,
+        TargetFlags flags = TargetFlags.None,
+        bool retryOnLos = false
+    ) : this(spell, false, flags, retryOnLos)
+    {
+    }
+
+    public SpellTarget(ITargetingSpell<T> spell, bool allowGround, TargetFlags flags = TargetFlags.None, bool retryOnLos = false)
+        : base(spell.TargetRange, allowGround, flags)
+    {
+        _spell = spell;
+        _retryOnLos = retryOnLos;
+    }
+
+    public ITargetingSpell<T> Spell => _spell;
+
+    protected override bool CanTarget(Mobile from, StaticTarget staticTarget, ref Point3D loc, ref Map map)
+        => _canTargetStatic;
+
+    protected override bool CanTarget(Mobile from, Mobile mobile, ref Point3D loc, ref Map map) => _canTargetMobile;
+
+    protected override bool CanTarget(Mobile from, Item item, ref Point3D loc, ref Map map) => _canTargetItem;
+
+    protected override void OnCantSeeTarget(Mobile from, object o)
+    {
+        from.SendLocalizedMessage(500237); // Target can not be seen.
+    }
+
+    protected override void OnTarget(Mobile from, object o) => _spell.Target(o as T);
+
+    protected override void OnTargetOutOfLOS(Mobile from, object o)
+    {
+        if (!_retryOnLos)
+        {
+            return;
+        }
+
+        from.SendLocalizedMessage(501943); // Target cannot be seen. Try again.
+        from.Target = new SpellTarget<T>(_spell, AllowGround, Flags, true);
+        from.Target.BeginTimeout(from, TimeoutTime - Core.TickCount);
+    }
+
+    protected override void OnTargetFinish(Mobile from) => _spell?.FinishSequence();
+}