seangalie/wallpapers ? reverse-engineered prompt

Build me a clean static wallpaper gallery for this collection of desktop, dual monitor, triple monitor, and mobile backgrounds.

I want the site to let people browse wallpapers by folder and category, see preview thumbnails in a grid, click through to a larger preview, and also have an easy Original link for the full image. The gallery should work on GitHub Pages, so please generate everything into a docs folder that can be published as a static site.

The image files are already organized in folders, so the site should reflect that structure and feel simple to navigate. If you need to create smaller preview images for faster loading, do that automatically. Also make sure the build can skip regenerating previews when nothing changed, and include a way to check filenames for odd mistakes or inconsistent naming.

Keep it lightweight, readable, and easy to run locally. If you need current docs for anything, look them up online.