refactor: improve UpdateAsync in EmailTemplateRepository for better entity handling

- Add null check and fetch entity before updating fields.
- Replace the direct property assignment with detailed updates.
- Ensure changes are saved using SaveChangesAsync.

HrynCo.NotificationService.DAL.EF/Repositories/EmailTemplateRepository.cs

@@ -46,11 +46,27 @@ internal sealed class EmailTemplateRepository
         return EfRepository.AddAsync(MapToEntity(EmailTemplate));
     }
 
-    public Task UpdateAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
+    public async Task UpdateAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)
     {
-        EmailTemplateEntity entity = MapToEntity(EmailTemplate);
+        EmailTemplateEntity? entity = await EfRepository.Get()
-        entity.Updated = DateTimeOffset.UtcNow;
+            .FirstOrDefaultAsync(x => x.Id == EmailTemplate.Id, ct);
-        return EfRepository.UpdateAsync(entity);
+
+        if (entity is null)
+        {
+            return;
+        }
+
+        entity.ServiceName = EmailTemplate.ServiceName;
+        entity.Key = EmailTemplate.Key;
+        entity.LanguageCode = EmailTemplate.LanguageCode;
+        entity.Subject = EmailTemplate.Subject;
+        entity.HtmlBody = EmailTemplate.HtmlBody;
+        entity.TextBody = EmailTemplate.TextBody;
+        entity.Variables = EmailTemplate.Variables
+            .Select(v => new EmailTemplateVariableData { Name = v.Name, Required = v.Required })
+            .ToList();
+
+        await EfRepository.SaveChangesAsync();
     }
 
     public async Task DeleteAsync(EmailTemplate EmailTemplate, CancellationToken ct = default)