feat: 优化存档管理，添加异步加载槽位摘要功能，减少主菜单等待时间

Assets/_Game/Scripts/Core/Save/GameSaveManager.cs

@@ -221,6 +221,9 @@ namespace BaseGames.Core.Save
         }
 
         // ── 存档槽摘要 ────────────────────────────────────────────────────────
+        /// <summary>
+        /// 仅解析 Meta 和 Player 两个顶层字段，避免反序列化整个 SaveData 造成不必要的 GC 压力。
+        /// </summary>
         public async Task<SlotSummary> GetSlotSummaryAsync(int slotIndex)
         {
             if (!_storage.Exists(slotIndex)) return null;
@@ -228,14 +231,14 @@ namespace BaseGames.Core.Save
             if (json == null) return null;
             try
             {
-                var data = JsonConvert.DeserializeObject<SaveData>(json);
+                var root = Newtonsoft.Json.Linq.JObject.Parse(json);
                 return new SlotSummary
                 {
                     SlotIndex    = slotIndex,
-                    Playtime     = data.Meta.Playtime,
-                    LastSaved    = data.Meta.LastSaved,
-                    SceneName    = data.Player?.Scene,
-                    ActiveFormId = data.Player?.ActiveFormId,
+                    Playtime     = root["Meta"]?["Playtime"]?.Value<float>() ?? 0f,
+                    LastSaved    = root["Meta"]?["LastSaved"]?.Value<string>(),
+                    SceneName    = root["Player"]?["Scene"]?.Value<string>(),
+                    ActiveFormId = root["Player"]?["ActiveFormId"]?.Value<string>(),
                 };
             }
             catch { return null; }

Assets/_Game/Scripts/Core/Save/LocalFileStorage.cs

@@ -25,10 +25,14 @@ namespace BaseGames.Core.Save
         public async Task WriteAsync(int slotIndex, string json)
         {
             var path = GetPath(slotIndex);
-            // 先写临时文件再原子性替换，防止写入中途断电损坏存档
+            // 先写临时文件再原子性替换，防止写入中途断电损坏存档。
+            // File.Replace 要求 destination 必须已存在；首次存档时直接 Move。
             var tmp = path + ".tmp";
             await File.WriteAllTextAsync(tmp, json);
-            File.Replace(tmp, path, path + ".bak", ignoreMetadataErrors: true);
+            if (File.Exists(path))
+                File.Replace(tmp, path, path + ".bak", ignoreMetadataErrors: true);
+            else
+                File.Move(tmp, path);
         }
 
         public async Task<string> ReadAsync(int slotIndex)

Assets/_Game/Scripts/Core/Save/SaveData.cs

@@ -34,7 +34,7 @@ namespace BaseGames.Core.Save
     [Serializable]
     public class SaveMeta
     {
-        public string Version      = "2.2";
+        public string Version      = SaveMigrator.CurrentVersion;
         public int    SlotIndex;
         public string LastSaved;        // ISO 8601
         public float  Playtime;