Add `cashu-ts` to Cashu project page

[dergigi]

See:

• https://cashu-ts.dev/
• https://github.com/cashubtc/cashu-ts
• https://opensats.org/blog/sixteenth-wave-of-bitcoin-grants#cashu-ts-and-coco

I think it's worth adding a short paragraph that mentions that we've funded multiple Cashu projects, including cashu-ts.