feat: add image lightbox to blog posts

[kOaDT]

Description

Allow readers to click on article images to view them in fullscreen with a semi-transparent overlay. Close with the X button, Escape key, or by clicking the backdrop.

I’ve been using your project for the write-ups of my web security lab over the past few months. Thanks a lot for your work! I'm really happy with it.
Today, I added a small feature that allows users to zoom in on images when clicking on them. Since I implemented it on my own fork, I’d be happy to share the modification with you if you’re interested.

If you’d like to see it live, you can check out a few images in this article:
https://koadt.github.io/oss-oopssec-store/posts/product-search-sql-injection/

I couldn’t find any existing issue related to this feature. Since I’ve already implemented it on my side, I’m submitting the code directly as a PR.
If it’s not something you’re interested in, feel free to close the PR 🙂

Types of changes

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Documentation Update (if none of the other choices apply)
• Others (any other types not listed above)

Checklist

• I have read the Contributing Guide
• I have added the necessary documentation (if appropriate)
• Breaking Change (fix or feature that would cause existing functionality to not work as expected)

Further comments

Related Issue

Closes: #