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/Document.cs

@@ -9,85 +9,77 @@ using System.Linq;
 #endif
 
 namespace EnvelopeGenerator.Domain.Entities
-#if NET
-    ;
-#elif NETFRAMEWORK
 {
-#endif
-
-[Table("TBSIG_ENVELOPE_DOCUMENT", Schema = "dbo")]
-public class Document : IHasEnvelope, IHasAddedWhen
-{
-    public Document()
+    [Table("TBSIG_ENVELOPE_DOCUMENT", Schema = "dbo")]
+    public class Document : IHasEnvelope, IHasAddedWhen
     {
+        public Document()
+        {
 #if NETFRAMEWORK
-        Elements = Enumerable.Empty<Signature>().ToList();
+            Elements = Enumerable.Empty<Signature>().ToList();
+#endif
+        }
+
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        [Column("GUID")]
+        public int Id { get; set; }
+
+        [Required]
+        [Column("ENVELOPE_ID")]
+        public int EnvelopeId { get; set; }
+#if NETFRAMEWORK
+            = 0;
+#endif
+
+        [Required]
+        [Column("ADDED_WHEN", TypeName = "datetime")]
+        public DateTime AddedWhen { get; set; }
+
+        [Column("BYTE_DATA", TypeName = "varbinary(max)")]
+        public byte[]
+#if nullable
+            ?
+#endif
+            ByteData { get; set; }
+
+        #region File
+        [Column("FILENAME", TypeName = "nvarchar(256)")]
+        public string Filename { get; set; }
+
+        [Column("FILEPATH", TypeName = "nvarchar(256)")]
+        public string Filepath { get; set; }
+
+        [Column("FILENAME_ORIGINAL", TypeName = "nvarchar(256)")]
+        public string
+#if nullable
+            ?
+#endif
+            FileNameOriginal { get; set; }
+        #endregion
+
+        public virtual List<Signature>
+#if nullable
+            ?
+#endif
+            Elements { get; set; }
+
+        [ForeignKey("EnvelopeId")]
+        public virtual Envelope
+#if nullable
+            ?
+#endif
+            Envelope { get; set; }
+
+#if NETFRAMEWORK
+        [NotMapped]
+        public bool IsTempFile { get; set; }
+
+        [NotMapped]
+        public Bitmap Thumbnail { get; set; }
+
+        [NotMapped]
+        public int PageCount { get; set; }
 #endif
     }
-
-    [Key]
-    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
-    [Column("GUID")]
-    public int Id { get; set; }
-
-    [Required]
-    [Column("ENVELOPE_ID")]
-    public int EnvelopeId { get; set; }
-#if NETFRAMEWORK
-        = 0;
-#endif
-
-    [Required]
-    [Column("ADDED_WHEN", TypeName = "datetime")]
-    public DateTime AddedWhen { get; set; }
-
-    [Column("BYTE_DATA", TypeName = "varbinary(max)")]
-    public byte[]
-#if nullable
-        ?
-#endif
-        ByteData { get; set; }
-
-    #region File
-    [Column("FILENAME", TypeName = "nvarchar(256)")]
-    public string Filename { get; set; }
-
-    [Column("FILEPATH", TypeName = "nvarchar(256)")]
-    public string Filepath { get; set; }
-
-    [Column("FILENAME_ORIGINAL", TypeName = "nvarchar(256)")]
-    public string
-#if nullable
-        ?
-#endif
-        FileNameOriginal { get; set; }
-    #endregion
-
-    public virtual List<Signature>
-#if nullable
-        ?
-#endif
-        Elements { get; set; }
-
-    [ForeignKey("EnvelopeId")]
-    public virtual Envelope
-#if nullable
-        ?
-#endif
-        Envelope { get; set; }
-
-#if NETFRAMEWORK
-    [NotMapped]
-    public bool IsTempFile { get; set; }
-
-    [NotMapped]
-    public Bitmap Thumbnail { get; set; }
-
-    [NotMapped]
-    public int PageCount { get; set; }
-#endif
-}
-
-#if NETFRAMEWORK
-    }
-#endif
+}