[Refactor] Replace enum-driven modifier system with data-driven SO composition

Replace the entire static, enum-based modifier pipeline with a
composition-based, data-driven architecture using ScriptableObject
polymorphism. New modifiers can now be created by assembling SO building
blocks (Conditions + Effects + Behaviors) — no core code edits needed.

New architecture:
- Core/: TriggerType, ModifierPhase, ModifierContext, ICondition, IEffect
- Definition/: ModifierDefinitionSO, ModifierBehaviorSO, ConditionSO, EffectSO, ModifierCatalogSO
- Conditions/: DieValueCondition, CategoryCondition, MinScoreCondition, DiceCountCondition
- Effects/: AddFlat, AddPerDie, Multiply, MultiplyPerDie, PostMultiply, AddCurrency, ConsumeCharge
- Runtime/: ModifierInstance, ModifierRegistry (non-static service)
- Pipeline/: async ModifierPipeline with phase ordering, tracing, anti-recursion
- Editor/: ModifierDefinitionValidator with menu items
- Events/: GameEventBus (non-static typed dispatcher)
- DI/: GameLifetimeScope (VContainer composition root)

Deleted old system: ModifierData, ModifierEffect, ModifierEnums,
ModifierPipeline (static), ModifierRuntime, ModifierTarget, ShopCatalog,
ModifierAssetCreator.

Updated: ScoringSystem (VContainer + async), InventoryModel (delegates to
ModifierRegistry), ShopModel (uses ModifierDefinitionSO), GameController
(VContainer injection), SaveData (uses Runtime.ModifierSaveEntry), all
views/controllers, and all test files.

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

Assets/Scripts/Modifiers/Effects/AddFlatScoreEffect.cs

@@ -0,0 +1,31 @@
+using Cysharp.Threading.Tasks;
+using UnityEngine;
+using YachtDice.Modifiers.Core;
+using YachtDice.Modifiers.Definition;
+using YachtDice.Modifiers.Runtime;
+
+namespace YachtDice.Modifiers.Effects
+{
+    [CreateAssetMenu(fileName = "AddFlatScoreEffect", menuName = "YachtDice/Modifiers/Effects/Add Flat Score")]
+    public class AddFlatScoreEffect : EffectSO
+    {
+        [SerializeField] private int value;
+
+        public override UniTask Apply(ModifierContext context, ModifierInstance instance)
+        {
+            context.FlatBonus += value * instance.Stacks;
+            return UniTask.CompletedTask;
+        }
+
+#if UNITY_EDITOR
+        public static AddFlatScoreEffect CreateForTest(int value, ModifierPhase phase = ModifierPhase.Additive, int priority = 0)
+        {
+            var so = CreateInstance<AddFlatScoreEffect>();
+            so.value = value;
+            so.SetPhaseForTest(phase);
+            so.SetPriorityForTest(priority);
+            return so;
+        }
+#endif
+    }
+}