Persist "Only mentions" between refreshes?

This is probably a niche request but I sometimes love *not* seeing favorites/reboosts in my notifications and it would be really nice if the "Only mentions" setting in https://phanpy.social/#/notifications persisted between refreshes.

Would you be interested in this feature? I have this working in a [fork](https://github.com/cheeaun/phanpy/compare/main...fasiha:phanpy:persist-mentions-only?expand=1), which does what you'd expect: saves this in localStorage and reinitializes this state in `notifications.jsx` from there. Happy to make this into a PR if you're open to it, with screenshots, etc.?