User handle input broken with some Android keyboards

[estrattonbailey]

This is not new, but we've managed to improve support for various keyboards in the composer, and we should return to this to see what we can do here.

https://github.com/bluesky-social/social-app/assets/4732330/f1ec0c2c-5e27-4b2f-b72f-48948dd3c720