clean: Article to Post in domain and related use cases

Renamed the 'Article' domain to 'Post' in order to better reflect the purpose and utility of the object. The change involved renaming all related use cases, classes, and other references from 'Article' to 'Post' and updating all functions and data types to work with Posts instead of Articles.

useCases/GetPostUseCase.go

@@ -0,0 +1,21 @@
+package useCases
+
+import (
+	"GohCMS2/adapters/secondary/gateways"
+	"GohCMS2/domain/post"
+	"gorm.io/gorm"
+)
+
+type GetArticleUseCase struct {
+	articleRepository gateways.PostRepository
+}
+
+func NewGetArticleUseCase(db *gorm.DB) *GetArticleUseCase {
+	return &GetArticleUseCase{
+		articleRepository: *gateways.NewPostRepository(db),
+	}
+}
+
+func (g *GetArticleUseCase) GetArticle(id uint32) (post.Post, error) {
+	return g.articleRepository.Get(id)
+}