Update EmailTemplateDto: add timestamps, make fields nullable

Removed ApiExplorerSettings attribute. Changed Body and Subject to nullable strings with init accessors and updated their documentation. Added AddedWhen and ChangedWhen timestamp properties to track template creation and modification dates. Cleaned up property formatting.

EnvelopeGenerator.Application/Common/Dto/EmailTemplateDto.cs

@@ -5,13 +5,12 @@ namespace EnvelopeGenerator.Application.Common.Dto
     /// <summary>
     /// 
     /// </summary>
-    [ApiExplorerSettings(IgnoreApi = true)]
     public record EmailTemplateDto
     {
         /// <summary>
         /// 
         /// </summary>
-        public int Id{ get; init; }
+        public int Id { get; init; }
 
         /// <summary>
         /// 
@@ -19,13 +18,23 @@ namespace EnvelopeGenerator.Application.Common.Dto
         public required string Name { get; init; }
 
         /// <summary>
-        /// 
+        /// Das Datum und die Uhrzeit, wann die Vorlage hinzugefügt wurde.
         /// </summary>
-        public required string Body { get; set; }
+        public DateTime AddedWhen { get; init; }
 
         /// <summary>
-        /// 
+        /// Der Inhalt (Body) der E-Mail-Vorlage. Kann null sein.
         /// </summary>
-        public required string Subject { get; set; }
+        public string? Body { get; init; }
+
+        /// <summary>
+        /// Der Betreff der E-Mail-Vorlage. Kann null sein.
+        /// </summary>
+        public string? Subject { get; init; }
+
+        /// <summary>
+        /// Das Datum und die Uhrzeit, wann die Vorlage zuletzt geändert wurde. Kann null sein.
+        /// </summary>
+        public DateTime? ChangedWhen { get; init; }
     };
 }