Added fallback save option for firefox

[jaalte]

Saving didn't work in firefox cause there's no file picker system, so I made it save it as spell.json if that first option fails. Tested on chromium and firefox.

[netlify[bot]]

✅ Deploy Preview for keen-boyd-1443aa ready!

Name	Link
🔨 Latest commit	0887a3bcb381f4329129a644f38cd7f1d501ba10
🔍 Latest deploy log	https://app.netlify.com/sites/keen-boyd-1443aa/deploys/64a0a7825e17b100089bf917
😎 Deploy Preview	https://deploy-preview-310--keen-boyd-1443aa.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[TodePond]

awesome!