Return "suggested articles" from post endpoint

When a post is queried on /content/post/{slug}, the frontend will need to display a list of three "related posts" - using the post slug, title, and authors.

{
  "relatedPosts": [
    {
      "slug": "post-slug",
      "title": "Post Title",
      "authors": [
        {
          "slug": "author-slug",
          "name": "Author Name"
        }
      ]
    }
  ],
}

The current frontend implementation of this exists here: https://github.com/playfulprogramming/playfulprogramming/blob/8b3908092fe61ea490afcf431cd471dde14b8865/src/utils/get-suggested-articles.ts#L72

This must be significantly optimized and ideally done in one query.

• This should exclude any posts in the same collection or groupId.
• Consider a vector similarity search on the post description.
• Consider the number of overlapping tags between the posts

Start at the /content/post/{slug} endpoint and read the current frontend reference in src/utils/get-suggested-articles.ts around line 72. Define how similarity and overlapping tags should select three posts while excluding the same collection or groupId, then verify the endpoint returns the specified slug, title, and author fields efficiently.