Add Linu.li to Demos

[immineal]

Hi! I'd like to add Linu.li to the Demos section.

It is a privacy-first toolbox that uses WebAssembly (via libraries like ffmpeg.wasm and various image codecs) to process files entirely in the browser without server uploads.

I have followed the formatting style [Name - Desc](Link) found in the Demos section.

Thanks!