OSD extension

### Feature Description

Would it be possible to have OSD show, when:
* NumLock is toggled (similarly to capslock being toggled)
* keyboard layout is changed

Thanks a lot!

### Use Case

_No response_

### Compositor(s)

- [x] All compositors
- [ ] Niri
- [ ] Hyprland
- [ ] MangoWC (dwl)
- [ ] Sway
- [ ] Other (specify below)

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_

Start by finding the existing CapsLock OSD behavior and the input or compositor entry points that expose NumLock and keyboard-layout changes. Done means the OSD reports both events consistently across the listed compositors; no specific files or tests are named in the issue.

Written by the indexing model from the issue text.