fix(admin): redirect to edit page after creating blog post

Root cause: after successful creation the form stayed on /blog/new.
User couldn't tell it worked, clicked Save again, the second attempt
hit the unique slug constraint and showed an error — making it look
like creation was broken.

Fix: adminPost is now typed, onSuccess redirects to /blog/{id} on new
posts so the user lands on the edit page immediately.

Also fixes commentCount being undefined in the list (MapPost now
includes comment count via eager-loaded Comments).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Meezi.Admin.API/Services/AdminWebsiteService.cs

@@ -15,7 +15,9 @@ public class AdminWebsiteService(AppDbContext db) : IAdminWebsiteService
         var q = db.WebsiteBlogPosts.AsQueryable();
         if (published.HasValue) q = q.Where(p => p.IsPublished == published.Value);
         var total = await q.CountAsync(ct);
-        var posts = await q.OrderByDescending(p => p.CreatedAt)
+        var posts = await q
+            .Include(p => p.Comments)
+            .OrderByDescending(p => p.CreatedAt)
             .Skip((page - 1) * limit).Take(limit).ToListAsync(ct);
         return new { Posts = posts.Select(MapPost), Total = total, Page = page, Limit = limit };
     }
@@ -162,5 +164,6 @@ public class AdminWebsiteService(AppDbContext db) : IAdminWebsiteService
         p.Id, p.Slug, p.TitleFa, p.TitleEn, p.ExcerptFa, p.ExcerptEn,
         p.ContentFa, p.ContentEn, p.CategoryFa, p.CategoryEn, p.Author,
         p.TagsJson, p.CoverImage, p.IsPublished, p.PublishedAt, p.ViewCount, p.CreatedAt,
+        CommentCount = p.Comments?.Count ?? 0,
     };
 }