feat: T2A defensive spells (#2378)

## Summary

Implements T2A-accurate mechanics for the three defensive spells based on UO98 demo scripts. Pre-UOR (`!Core.UOR`) triggers the new behavior; UOR and AOS paths are unchanged.

- **Reactive Armor**: percentage-based melee damage reflection (10-35% based on target Magery), targeted, timed (25-75s). Guards exempt, ranged attacks beyond 1 tile unaffected. Reflected damage is sourceless.
- **Protection**: temporary AC bonus (casterMagery/10, 1-10 AR) via VirtualArmorMod, targeted, timed (12-120s). Shared table with Arch Protection — only one protection buff per mobile.
- **Magic Reflect**: single-use spell reflection using MagicDamageAbsorb as a flag. No timer, no DefensiveSpell lock. Consumed on first reflected spell.
- **Arch Protection**: T2A path applies Protection via shared table with area sound (0x1F7 vs 0x1ED).
- No DefensiveSpell mutual exclusion for T2A — all three spells operate independently.

## Test plan

- [x] Set expansion to T2A
- [x] Cast Reactive Armor on self → verify particles (0x376A) and sound (0x1F2)
- [x] Get hit in melee → verify attacker takes reflected damage with spark effect and sound
- [x] Get hit by ranged weapon from > 1 tile → verify no reflection
- [x] Wait for RA to expire → verify effect ends silently
- [x] Cast RA on target that already has it → verify "This spell is already in effect"
- [x] Cast Protection on another player → verify particles (0x375A) and sound (0x1ED)
- [x] Check target's AR → verify it increased by casterMagery/10
- [x] Wait for Protection to expire → verify AR returns to normal
- [x] Cast Protection on self, then cast Protection on another player → verify both succeed
- [x] Cast Arch Protection on ground near allies → verify each gets AR bonus with sound 0x1F7
- [x] Cast Arch Protection near a target already protected → verify that target is skipped
- [x] Cast Magic Reflect on self → verify particles (0x375A) and sound (0x1E9)
- [x] Have an enemy cast a harmful spell at you → verify spell reflects back, effect consumed
- [x] Cast Magic Reflect again → verify it can be recast after consumption
- [x] Cast Magic Reflect when already active → verify "This spell is already in effect"
- [x] Verify all three spells can be active simultaneously on the same mobile
- [x] Switch expansion to UOR → verify existing UOR behavior unchanged
- [x] Switch expansion to AOS → verify existing AOS behavior unchanged

Projects/UOContent/Spells/Fifth/MagicReflect.cs

@@ -38,6 +38,11 @@ namespace Server.Spells.Fifth
                 return false;
             }
 
+            if (!Core.UOR)
+            {
+                return true;
+            }
+
             if (!Caster.CanBeginAction<DefensiveSpell>())
             {
                 Caster.SendLocalizedMessage(1005385); // The spell will not adhere to you at this time.
@@ -105,6 +110,20 @@ namespace Server.Spells.Fifth
                     }
                 }
             }
+            else if (!Core.UOR)
+            {
+                if (Caster.MagicDamageAbsorb > 0)
+                {
+                    Caster.SendLocalizedMessage(1005559); // This spell is already in effect.
+                }
+                else if (CheckSequence())
+                {
+                    Caster.MagicDamageAbsorb = 1;
+
+                    Caster.FixedParticles(0x375A, 10, 15, 5037, EffectLayer.Waist);
+                    Caster.PlaySound(0x1E9);
+                }
+            }
             else
             {
                 if (Caster.MagicDamageAbsorb > 0)