input doesn't handle NUM_LOCK properly on Windows

### Describe the bug

`Text` is `""` if numlock is enabled on the keyboard.

Culprit: https://github.com/charmbracelet/x/blob/19b66ab4499be69e337700b9adf0c550a47830ba/input/driver_windows.go#L468-L471

`cks` is 0x20 (I think) when numlock is pressed.

### Setup

- Windows 10
- Windows Terminal

### To Reproduce

I tested with github.com/stt/opencode. I can't type into the prompt box unless I turn off numlock on my keyboard.

### Source Code

I don't have a minimal repro, sorry.

### Expected behavior

numlock should not affect the input of normal characters (a-z keys).

Start in input/driver_windows.go at lines 468-471 and inspect how the cks value is handled when Num Lock is enabled. Reproduce the issue on Windows 10 in Windows Terminal with Num Lock on, then verify that normal a-z input produces non-empty Text without being affected by Num Lock.

Written by the indexing model from the issue text.