fix: update week calculation to start from Saturday

src/CMSMicroservice.Application/CommissionCQ/Queries/GetAvailableWeeks/GetAvailableWeeksQueryHandler.cs

@@ -110,13 +110,34 @@ public class GetAvailableWeeksQueryHandler : IRequestHandler<GetAvailableWeeksQu
 
     private static string GetWeekNumber(DateTime date)
     {
-        var calendar = CultureInfo.InvariantCulture.Calendar;
-        var weekOfYear = calendar.GetWeekOfYear(
-            date, 
-            CalendarWeekRule.FirstDay, 
-            DayOfWeek.Saturday);
+        var year = date.Year;
         
-        return $"{date.Year}-W{weekOfYear:D2}";
+        // پیدا کردن اولین شنبه سال
+        var jan1 = new DateTime(year, 1, 1);
+        var jan1DayOfWeek = (int)jan1.DayOfWeek; // 0=Sunday, 1=Monday, ..., 6=Saturday
+        
+        // محاسبه تعداد روزهایی که باید اضافه کنیم تا به اولین شنبه برسیم
+        var daysToFirstSaturday = jan1DayOfWeek == 6 ? 0 : (6 - jan1DayOfWeek + 7) % 7;
+        var firstSaturday = jan1.AddDays(daysToFirstSaturday);
+        
+        // پیدا کردن شنبه شروع هفته جاری
+        var currentDayOfWeek = (int)date.DayOfWeek; // 0=Sun, 1=Mon, ..., 6=Sat
+        var daysToCurrentSaturday = currentDayOfWeek == 6 ? 0 : (currentDayOfWeek + 1) % 7;
+        var weekStartSaturday = date.Date.AddDays(-daysToCurrentSaturday);
+        
+        // محاسبه شماره هفته
+        int weekNum;
+        if (weekStartSaturday < firstSaturday)
+        {
+            weekNum = 1; // هفته اول سال
+        }
+        else
+        {
+            var daysSinceFirstSaturday = (weekStartSaturday - firstSaturday).Days;
+            weekNum = (daysSinceFirstSaturday / 7) + 1;
+        }
+        
+        return $"{year}-W{weekNum:D2}";
     }
 
     private static (DateTime startDate, DateTime endDate) GetWeekRange(DateTime date)