Fix keypad input not working in TUI textarea component

[neominik]

First off, thanks for creating such a great tool! I noticed that input via the keypad/numpad wasn't working so here is a fix. Tested locally and seems to be working fine.

Since I'm not familiar with the libraries used, it might well be the case that there are cleaner ways to implement this. In that case, we can throw away this attempt and create an issue for a proper fix.