Make EmailTemplateDto mutable, add LangCode property

Changed EmailTemplateDto properties from init-only to mutable (get/set), removed 'required' from Name, and added a new LangCode property with a default value. Also updated using directives and added conditional compilation in EmailTemplate.cs for .NET Framework compatibility. No functional changes to EmailTemplate class.

EnvelopeGenerator.Application/Common/Dto/EmailTemplateDto.cs

@@ -13,25 +13,30 @@ public record EmailTemplateDto
     /// <summary>
     /// 
     /// </summary>
-    public required string Name { get; init; }
+    public string Name { get; set; } = null!;
 
     /// <summary>
     /// Das Datum und die Uhrzeit, wann die Vorlage hinzugefügt wurde.
     /// </summary>
-    public DateTime AddedWhen { get; init; }
+    public DateTime AddedWhen { get; set; }
 
     /// <summary>
     /// Der Inhalt (Body) der E-Mail-Vorlage. Kann null sein.
     /// </summary>
-    public string? Body { get; init; }
+    public string? Body { get; set; }
 
     /// <summary>
     /// Der Betreff der E-Mail-Vorlage. Kann null sein.
     /// </summary>
-    public string? Subject { get; init; }
+    public string? Subject { get; set; }
+
+    /// <summary>
+    /// Der Sprachcode der E-Mail-Vorlage.
+    /// </summary>
+    public string LangCode { get; set; } = null!;
 
     /// <summary>
     /// Das Datum und die Uhrzeit, wann die Vorlage zuletzt geändert wurde. Kann null sein.
     /// </summary>
-    public DateTime? ChangedWhen { get; init; }
+    public DateTime? ChangedWhen { get; set; }
 };

EnvelopeGenerator.Domain/Entities/EmailTemplate.cs

@@ -1,9 +1,11 @@
-using System;
-using DigitalData.Core.Abstractions.Interfaces;
+using DigitalData.Core.Abstractions.Interfaces;
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
 using EnvelopeGenerator.Domain.Interfaces.Auditing;
+#if NETFRAMEWORK
+using System;
+#endif
 
 namespace EnvelopeGenerator.Domain.Entities
 {