fix: all remaining "article" replaced by "post"

All instances of the term "article" were replaced with "post" in variable names, type names, function names, etc. This was primarily to ensure consistent naming and reduce confusion going forward. The term "post" was chosen as it's a more commonly used term for the involved operations in the context of content management and blogging platforms. All tests were also updated to reflect these changes.

domain/gateways/IPostRepository.go

@@ -4,8 +4,8 @@ import (
 	"GohCMS2/domain/post"
 )
 
-type IArticleRepository interface {
+type IPostRepository interface {
 	Get(id uint32) (post.Post, error)
 	GetAll() []post.Post
-	Create(article post.Post) (post.Post, error)
+	Create(post post.Post) (post.Post, error)
 }