fix(blog): auto-generate slug when admin leaves it empty

Allow optional slug on create/update, generate from title with unique fallback,
so BackOffice can publish posts without manual slug entry.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/CMSMicroservice.Application/BlogPostCQ/Commands/CreateBlogPost/CreateBlogPostCommandHandler.cs

@@ -1,3 +1,4 @@
+using CMSMicroservice.Application.Common;
 using CMSMicroservice.Application.Common.FileManager;
 using CMSMicroservice.Application.Common.Interfaces;
 using CMSMicroservice.Domain.Entities.Blog;
@@ -32,12 +33,13 @@ public class CreateBlogPostCommandHandler : IRequestHandler<CreateBlogPostComman
         if (string.IsNullOrEmpty(currentUserId) || !long.TryParse(currentUserId, out var authorUserId))
             throw new UnauthorizedAccessException("کاربر احراز هویت نشده است");
 
+        var slug = BlogSlugHelper.ResolveForCreate(request.Slug, request.Title.Trim());
+        slug = await BlogSlugHelper.EnsureUniquePostSlugAsync(_context, slug, cancellationToken: cancellationToken);
+
         var post = new BlogPost
         {
             Title = request.Title.Trim(),
-            Slug = string.IsNullOrWhiteSpace(request.Slug)
-                ? $"post-{Guid.NewGuid():N}".Substring(0, 20)
-                : request.Slug.Trim().ToLower(),
+            Slug = slug,
             Summary = request.Summary?.Trim(),
             HtmlContent = request.HtmlContent,
             FeaturedImagePath = request.FeaturedImagePath,