Billing: Add possibility to automatically add business shares

Elwig/Models/Entities/Season.cs

@@ -55,6 +55,14 @@ namespace Elwig.Models.Entities {
             set => PenaltyNoneValue = value != null ? DecToDb(value.Value) : null;
         }
 
+        [Column("bs_value")]
+        public long? BusinessShareValueValue { get; set; }
+        [NotMapped]
+        public decimal? BusinessShareValue {
+            get => BusinessShareValueValue != null ? DecFromDb(BusinessShareValueValue.Value) : null;
+            set => BusinessShareValueValue = value != null ? DecToDb(value.Value) : null;
+        }
+
         [Column("start_date")]
         public string? StartDateString { get; set; }