[Rename] Unify Die → Dice naming across the entire project

Standardize all class, interface, file, method, event, field, and variable
names from the inconsistent "Die" form to "Dice", matching the existing
DiceManager/DiceCatalog/DiceCollection convention.

Renamed files (7 + meta): IDie→IDice, DieInstance→DiceInstance,
DieDefinitionSO→DiceDefinitionSO, StandardDieSO→StandardDiceSO,
DieValueCondition→DiceValueCondition, AddPerDieEffect→AddPerDiceEffect,
MultiplyPerDieEffect→MultiplyPerDiceEffect.

Updated all 31 consumer and test files with matching reference changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Assets/Scripts/Tests/Editor/ModifierPipelineTests.cs

@@ -186,8 +186,8 @@ namespace YachtDice.Tests
         [Test]
         public void Execute_MultipleModifiers_CorrectOrder()
         {
-            var perDieAdd = AddPerDieEffect.CreateForTest(2, targetDieValue: 3, phase: ModifierPhase.Additive);
-            var perDieMul = MultiplyPerDieEffect.CreateForTest(1.5f, targetDieValue: 3, phase: ModifierPhase.Multiplicative);
+            var perDieAdd = AddPerDiceEffect.CreateForTest(2, targetDiceValue: 3, phase: ModifierPhase.Additive);
+            var perDieMul = MultiplyPerDiceEffect.CreateForTest(1.5f, targetDiceValue: 3, phase: ModifierPhase.Multiplicative);
             var flatAdd = AddFlatScoreEffect.CreateForTest(10, ModifierPhase.Additive, priority: 10);
             var finalMul = MultiplyScoreEffect.CreateForTest(2f, ModifierPhase.Multiplicative, priority: 10);
 
@@ -283,12 +283,12 @@ namespace YachtDice.Tests
             Assert.IsTrue(result.DebugLog.Count > 0);
         }
 
-        // ── DieValue Condition ──────────────────────────────────────
+        // ── DiceValue Condition ──────────────────────────────────────
 
         [Test]
-        public void Execute_DieValueCondition_OnlyTriggersOnMatch()
+        public void Execute_DiceValueCondition_OnlyTriggersOnMatch()
         {
-            var condition = DieValueCondition.CreateForTest(6, minCount: 3);
+            var condition = DiceValueCondition.CreateForTest(6, minCount: 3);
             var effect = AddFlatScoreEffect.CreateForTest(100);
 
             var def = CreateDef("sixes-bonus", TriggerType.OnCategoryScored,