[Add] Universal modifier system, shop, inventory & persistence

Replace hardcoded BonusForOnes/MultiplierForSixes with data-driven
modifier system supporting 2 scopes (SelectedCategory, AnyCategoryClosed),
4 effect types, durability modes (Permanent, LimitedUses), and
configurable targets via ScriptableObject (ModifierData).

- Modifier domain: ModifierEnums, ModifierTarget, ModifierData,
  ModifierRuntime, ModifierEffect (dict-based strategy), ModifierPipeline
  (4-pass: cat-additive → cat-multiplicative → final-additive → final-multiplicative)
- ScoringSystem: replaced old modifier list with ModifierPipeline integration,
  added OnCategoryConfirmed event
- Shop MVC: ShopCatalog (SO), ShopModel, ShopView, ShopItemView, ShopController
- Inventory MVC: InventoryModel (activate/deactivate/sell/durability),
  InventoryView, InventorySlotView, InventoryController
- CurrencyBank: editor-adjustable balance with events
- Persistence: SaveData + SaveSystem (Newtonsoft JSON + PlayerPrefs)
- Editor: ModifierAssetCreator menu item to generate 6 example modifiers + catalog
- Tests: 6 test classes covering effects, pipeline, scoring, shop, inventory, save
- GameController: wired shop/inventory/save lifecycle
- GameInfoView: added currency display, shop/inventory toggle buttons

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

Assets/Scripts/Economy/CurrencyBank.cs

@@ -0,0 +1,44 @@
+using System;
+using UnityEngine;
+
+public sealed class CurrencyBank : MonoBehaviour
+{
+    [SerializeField] private int startingBalance = 500;
+
+    private int balance;
+
+    public int Balance => balance;
+
+    public event Action<int> OnBalanceChanged;
+
+    private void Awake()
+    {
+        balance = startingBalance;
+    }
+
+    public void Add(int amount)
+    {
+        if (amount <= 0) return;
+
+        balance += amount;
+        OnBalanceChanged?.Invoke(balance);
+    }
+
+    public bool Spend(int amount)
+    {
+        if (amount <= 0) return false;
+        if (balance < amount) return false;
+
+        balance -= amount;
+        OnBalanceChanged?.Invoke(balance);
+        return true;
+    }
+
+    public bool CanAfford(int amount) => balance >= amount;
+
+    public void SetBalance(int value)
+    {
+        balance = Mathf.Max(0, value);
+        OnBalanceChanged?.Invoke(balance);
+    }
+}