Ths Pull Request implements the ability to create new blog posts via the /posts endpoint. It includes:

1. Description field added to the Post model
2. A new method CreatePost in PostService to persist posts to the database
3. Slug generated from the post title (URL-friendly)
4. Returns 400 Bad Request if title or description is missing
5. The update supports the front-end form at /posts/new and ensures posts are saved in PostgreSQL.