Refactor entities: remove preprocessor directives, unify style

Large-scale cleanup of entity and interface classes:
- Removed obsolete #if NET/NETFRAMEWORK preprocessor blocks
- Unified class/property formatting and indentation
- Standardized use of data annotations
- Improved nullable reference type handling
- Simplified interfaces (IHasEnvelope, IHasReceiver)
- Removed redundant and dead code
- No changes to business logic or data model

These changes modernize and standardize the codebase for easier maintenance and .NET compatibility.

EnvelopeGenerator.Domain/Entities/History.cs

@@ -7,74 +7,66 @@ using EnvelopeGenerator.Domain.Constants;
 using DigitalData.Core.Abstractions.Interfaces;
 
 namespace EnvelopeGenerator.Domain.Entities
-#if NET
-    ;
-#elif NETFRAMEWORK
 {
+    [Table("TBSIG_ENVELOPE_HISTORY", Schema = "dbo")]
+    public class History : IHasEnvelope, IHasReceiver, IEntity, IHasAddedWhen, IHasChangedWhen
+    {
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        [Column("GUID")]
+        public long Id { get; set; }
+
+        [Required]
+        [Column("ENVELOPE_ID")]
+        public int EnvelopeId { get; set; }
+
+        [Required]
+        [Column("USER_REFERENCE", TypeName = "nvarchar(128)")]
+        public string UserReference { get; set; }
+
+        [Required]
+        [Column("STATUS")]
+        public EnvelopeStatus  Status { get; set; }
+
+        [Required]
+        [Column("ADDED_WHEN", TypeName = "datetime")]
+        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
+        public DateTime AddedWhen { get; set; }
+
+        [Column("ACTION_DATE", TypeName = "datetime")]
+        public DateTime? ChangedWhen { get; set; }
+        
+        [Column("COMMENT", TypeName = "nvarchar(max)")]
+        public string
+#if nullable
+            ?
 #endif
+            Comment { get; set; }
 
-[Table("TBSIG_ENVELOPE_HISTORY", Schema = "dbo")]
-public class History : IHasEnvelope, IHasReceiver, IEntity, IHasAddedWhen, IHasChangedWhen
-{
-    [Key]
-    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
-    [Column("GUID")]
-    public long Id { get; set; }
-
-    [Required]
-    [Column("ENVELOPE_ID")]
-    public int EnvelopeId { get; set; }
-
-    [Required]
-    [Column("USER_REFERENCE", TypeName = "nvarchar(128)")]
-    public string UserReference { get; set; }
-
-    [Required]
-    [Column("STATUS")]
-    public EnvelopeStatus  Status { get; set; }
-
-    [Required]
-    [Column("ADDED_WHEN", TypeName = "datetime")]
-    [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
-    public DateTime AddedWhen { get; set; }
-
-    [Column("ACTION_DATE", TypeName = "datetime")]
-    public DateTime? ChangedWhen { get; set; }
-    
-    [Column("COMMENT", TypeName = "nvarchar(max)")]
-    public string
-#if NET
-        ?
+        [ForeignKey("EnvelopeId")]
+        public virtual Envelope
+#if nullable
+            ?
 #endif
-        Comment { get; set; }
+            Envelope { get; set; }
 
-    [ForeignKey("EnvelopeId")]
-    public virtual Envelope
-#if NET
-        ?
+        [ForeignKey("UserReference")]
+        public virtual User
+#if nullable
+            ?
 #endif
-        Envelope { get; set; }
+            Sender { get; set; }
 
-    [ForeignKey("UserReference")]
-    public virtual User
-#if NET
-        ?
+        [ForeignKey("UserReference")]
+        public virtual Receiver
+#if nullable
+            ?
 #endif
-        Sender { get; set; }
-
-    [ForeignKey("UserReference")]
-    public virtual Receiver
-#if NET
-        ?
-#endif
-        Receiver { get; set; }
+            Receiver { get; set; }
 
 #if NETFRAMEWORK
-    [NotMapped]
-    public string StatusTranslated => My.Resources.Model.ResourceManager.GetString(Status.ToString());
+        [NotMapped]
+        public string StatusTranslated => My.Resources.Model.ResourceManager.GetString(Status.ToString());
 #endif
-}
-
-#if NETFRAMEWORK
     }
-#endif
+}