feat: better demo site (#1241)

* demo: add image-gallery post

* demo: change language weight

* demo: add multilanguage about page

* demo: change title and url

* demo: add shortcode documentation with multi-language support

* demo: improve markdown guide post

* demo: improve Math Typesetting post

* demo: rename Markdown Syntax Guide post

* demo: remove emoji support post

* demo: remove placeholder text post

* demo: remove rich-content post

* demo: rename image gallery page bundle

* demo: add multilingual `Documentation` category

* demo: Increase pagination pager size from 3 to 5.

* demo: add multilingual links, search, and archives pages

* demo: remove `ar` from demosite

demo/content/post/Image Gallery/index.md

@@ -0,0 +1,42 @@
+---
+title: Image Gallery
+description: Showcasing the built-in image gallery support
+date: 2026-01-26
+slug: image-gallery
+image: helena-hertz-wWZzXlDpMog-unsplash.jpg
+categories:
+    - Documentation
+tags:
+    - Gallery
+    - Photoswipe
+toc: false
+---
+
+Stack theme has a built-in support for image galleries. It allows you to create a beautiful gallery by simply placing multiple images side-by-side.
+
+## Sample Gallery
+
+![Photo by Florian Klauer on Unsplash](florian-klauer-nptLmg6jqDo-unsplash.jpg)  ![Photo by Luca Bravo on Unsplash](luca-bravo-alS7ewQ41M8-unsplash.jpg) 
+
+![Photo by Helena Hertz on Unsplash](helena-hertz-wWZzXlDpMog-unsplash.jpg)  ![Photo by Hudai Gayiran on Unsplash](hudai-gayiran-3Od_VKcDEAA-unsplash.jpg)
+
+## How it works
+
+The gallery is powered by **Photoswipe** and a custom internal script. It automatically calculates the best layout for your images based on their aspect ratios.
+
+To create a gallery, you just need to put multiple images in the same line (or paragraph).
+
+### Syntax
+
+```markdown
+![Image 1](image1.jpg)  ![Image 2](image2.jpg)
+
+![Image 3](image3.jpg)  ![Image 4](image4.jpg)
+```
+
+> **Note**: There should be two spaces between the images to ensure they stay in the same line in Markdown
+
+---
+
+Gallery Syntax inspired by [Typlog](https://typlog.com/)
+