Rework shop to support multiple item types and add unified PlayerModel

Generalize the shop from selling only ModifierDefinition to any IShopItem
(modifiers + dice). Add purchase condition checks, hover tooltips, and
fixed prices. Introduce PlayerModel as a facade over CurrencyBank,
InventoryModel, and DiceCollection for centralized state and save/load.

New files:
- IShopItem interface for purchasable items
- ShopCatalog SO (unified catalog for all item types)
- ShopTooltipView (description on hover)
- PlayerModel (aggregates player state)
- DiceCollection (owned dice tracking)
- DiceCatalog SO (dice definition registry)
- DiceCollectionTests

Modified:
- ModifierDefinition/DieDefinitionSO implement IShopItem
- ShopModel/ShopView/ShopItemView/ShopController use IShopItem
- SaveData v3 with OwnedDiceIds
- GameController uses PlayerModel for save/load
- GameLifetimeScope registers new services

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

Assets/Scripts/Shop/ShopController.cs

@@ -1,7 +1,6 @@
 using UnityEngine;
 using VContainer;
 using YachtDice.Economy;
-using YachtDice.Modifiers.Definition;
 
 namespace YachtDice.Shop
 {
@@ -9,14 +8,14 @@ namespace YachtDice.Shop
     {
         [SerializeField] private ShopView shopView;
 
-        private ModifierCatalog catalog;
+        private ShopCatalog catalog;
         private CurrencyBank currencyBank;
         private ShopModel model;
 
-        public ModifierCatalog Catalog => catalog;
+        public ShopCatalog Catalog => catalog;
 
         [Inject]
-        public void Construct(ModifierCatalog catalog, CurrencyBank currencyBank, ShopModel model)
+        public void Construct(ShopCatalog catalog, CurrencyBank currencyBank, ShopModel model)
         {
             this.catalog = catalog;
             this.currencyBank = currencyBank;
@@ -55,9 +54,9 @@ namespace YachtDice.Shop
                 shopView.Show();
         }
 
-        private void HandleBuyClicked(ModifierDefinition def)
+        private void HandleBuyClicked(IShopItem item)
         {
-            model.TryPurchase(def);
+            model.TryPurchase(item);
         }
 
         private void HandleCurrencyChanged(int newBalance)
@@ -66,7 +65,7 @@ namespace YachtDice.Shop
             shopView.RefreshStates(catalog.All, model);
         }
 
-        private void HandleItemPurchased(ModifierDefinition def)
+        private void HandleItemPurchased(IShopItem item)
         {
             shopView.RefreshStates(catalog.All, model);
         }