refactor(admin): migrate post,tag,user,category management to one Controller and resource routing

[Nima8FT]

• Replaced individual admin routes with Route::resource.
• Merged IndexController and CreateController into a unified Controller.
• Updated admin panel logic and views to use the new controller structure.
• Cleaned up old controller references and improved overall route organization.

Fix https://github.com/gomzyakov/laravel-blog/issues/476