feat(bll, dal): WeekendDayService + БД. CalendarService - получение рабочих дней за период

PARR.DAL/Models/WeekendDay.cs

@@ -0,0 +1,21 @@
+using PARR.DAL.Models.Base;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace PARR.DAL.Models
+{
+    [Table("WeekendDays")]
+    public class WeekendDay : IBase
+    {
+        [Key]
+        public Guid Id { get; set; }
+
+        [NotMapped]
+        public DateTimeOffset DateCreated { get; set; }
+
+        [NotMapped]
+        public DateTimeOffset? DateModified { get; set; }
+
+        public DateOnly Date { get; set; }
+    }
+}