Add ISender extension methods for reading email templates

Introduced ReadEmailTemplateQueryExtensions with methods to fetch a single EmailTemplateDto by ID or type and language code. Added required using directive for EnvelopeGenerator.Application.Common.Extensions. These extensions streamline querying email templates via ISender.

EnvelopeGenerator.Application/EmailTemplates/Queries/ReadEmailTemplateQuery.cs

@@ -6,6 +6,7 @@ using EnvelopeGenerator.Domain.Entities;
 using Microsoft.EntityFrameworkCore;
 using EnvelopeGenerator.Domain.Constants;
 using DigitalData.Core.Exceptions;
+using EnvelopeGenerator.Application.Common.Extensions;
 
 namespace EnvelopeGenerator.Application.EmailTemplates.Queries;
 
@@ -41,6 +42,40 @@ public record ReadEmailTemplateQuery : IEmailTemplateQuery, IRequest<IEnumerable
     public string? LangCode { get; set; }
 }
 
+/// <summary>
+/// 
+/// </summary>
+public static class ReadEmailTemplateQueryExtensions
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="sender"></param>
+    /// <param name="id"></param>
+    /// <param name="langCode"></param>
+    /// <param name="cancel"></param>
+    /// <returns></returns>
+    public static async Task<EmailTemplateDto?> ReadEmailTemplateById(this ISender sender, int id, string langCode, CancellationToken cancel = default)
+    {
+        var result = await sender.Send(new ReadEmailTemplateQuery { Id = id, LangCode = langCode }, cancel);
+        return result.FirstOrDefault();
+    }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="sender"></param>
+    /// <param name="type"></param>
+    /// <param name="langCode"></param>
+    /// <param name="cancel"></param>
+    /// <returns></returns>
+    public static async Task<EmailTemplateDto?> ReadEmailTemplateByType(this ISender sender, EmailTemplateType type, string langCode, CancellationToken cancel = default)
+    {
+        var result = await sender.Send(new ReadEmailTemplateQuery { Type = type, LangCode = langCode }, cancel);
+        return result.FirstOrDefault();
+    }
+}
+
 /// <summary>
 /// 
 /// </summary>