Add PositionCount property to Backtest models and responses

- Introduced PositionCount to Backtest, LightBacktest, and their respective response models.
- Updated BacktestController and BacktestExecutor to include PositionCount in responses.
- Modified database schema to accommodate new PositionCount field in relevant entities.

src/Managing.Api/Controllers/BacktestController.cs

@@ -316,7 +316,8 @@ public class BacktestController : BaseController
                 Score = b.Score,
                 ScoreMessage = b.ScoreMessage,
                 InitialBalance = b.InitialBalance,
-                NetPnl = b.NetPnl
+                NetPnl = b.NetPnl,
+                PositionCount = b.PositionCount
             }),
             TotalCount = totalCount,
             CurrentPage = page,
@@ -457,7 +458,8 @@ public class BacktestController : BaseController
                 Score = b.Score,
                 ScoreMessage = b.ScoreMessage,
                 InitialBalance = b.InitialBalance,
-                NetPnl = b.NetPnl
+                NetPnl = b.NetPnl,
+                PositionCount = b.PositionCount
             }),
             TotalCount = totalCount,
             CurrentPage = page,

src/Managing.Api/Models/Requests/LightBacktestResponse.cs

@@ -22,6 +22,7 @@ public class LightBacktestResponse
     [Required] public string ScoreMessage { get; set; } = string.Empty;
     [Required] public decimal InitialBalance { get; set; }
     [Required] public decimal NetPnl { get; set; }
+    [Required] public int PositionCount { get; set; }
 }
 
 public static class LightBacktestResponseMapper
@@ -45,7 +46,8 @@ public static class LightBacktestResponseMapper
             Score = b.Score,
             ScoreMessage = b.ScoreMessage,
             InitialBalance = b.InitialBalance,
-            NetPnl = b.NetPnl
+            NetPnl = b.NetPnl,
+            PositionCount = b.PositionCount
         };
     }
 }