Refactor, cleanup code and add documentaiton

Assets/Scripts/CardSystem/Data/CardCollectionState.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using AppleHills.Data.CardSystem;
+
+namespace Data.CardSystem
+{
+    /// <summary>
+    /// Serializable snapshot of the card collection state for save/load operations.
+    /// </summary>
+    [System.Serializable]
+    public class CardCollectionState
+    {
+        public int boosterPackCount;
+        public List<SavedCardEntry> cards = new List<SavedCardEntry>();
+        public List<SavedCardEntry> pendingRevealCards = new List<SavedCardEntry>();
+        public List<string> placedInAlbumCardIds = new List<string>();
+    }
+
+    /// <summary>
+    /// Serializable representation of a single card's saved data.
+    /// </summary>
+    [System.Serializable]
+    public class SavedCardEntry
+    {
+        public string definitionId;
+        public CardRarity rarity;
+        public int copiesOwned;
+    }
+}