Page up/down to navigate lists and grids skips some rows

### What Happened?

The first screen recording shows the problem on the Updates page, moving focus between installed apps displayed on a grid. Note that if I use arrow keys, it works as expected; only Page Up/Down skips rows.

https://github.com/user-attachments/assets/4b6d754c-6268-42cc-94b7-14fdd0fe3a79

The second video shows the same behavior happening elsewhere, in the app page list of links.

https://github.com/user-attachments/assets/053d6d11-d3e8-457b-8e42-f3dae662c8a7

### Steps to Reproduce

1. Go to the Updates page.
2. Press Tab until any app on the grid below is focused.
3. Press Page Down to move down the first column. _(it should skip a row for each step)_
4. Press Page Up to move up the first column. _(it should focus every row as expected)_
5. Move right to the second column, and try to repeat steps 3 and 4 there. _(it should display the same behavior of the other column, but inverted — i.e. moving up will skip, but down will not)_

### Expected Behavior

Moving focus with Page Up/Down should not skip rows.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Secure Session (Wayland, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

_No response_