fix: update week calculation to use Saturday as the start of the week

src/CMSMicroservice.Application/CommissionCQ/Commands/CalculateWeeklyBalances/CalculateWeeklyBalancesCommandHandler.cs

@@ -279,10 +279,13 @@ public class CalculateWeeklyBalancesCommandHandler : IRequestHandler<CalculateWe
         var year = int.Parse(parts[0]);
         var week = int.Parse(parts[1].Replace("W", ""));
 
-        // محاسبه اولین روز هفته (شنبه)
+        // محاسبه اولین شنبه سال
         var jan1 = new DateTime(year, 1, 1);
-        var daysOffset = DayOfWeek.Saturday - jan1.DayOfWeek;
-        var firstSaturday = jan1.AddDays(daysOffset);
+        var jan1DayOfWeek = (int)jan1.DayOfWeek;
+        // اگر 1 ژانویه شنبه باشد: offset=0، اگر یکشنبه: offset=6، دوشنبه: offset=5، ...
+        var daysToFirstSaturday = jan1DayOfWeek == 6 ? 0 : (6 - jan1DayOfWeek + 7) % 7;
+        var firstSaturday = jan1.AddDays(daysToFirstSaturday);
+        
         var weekStart = firstSaturday.AddDays((week - 1) * 7);
         var weekEnd = weekStart.AddDays(6).AddHours(23).AddMinutes(59).AddSeconds(59);