[Feature]: MX Keys S - reset F-keys binding

### Pre-flight checklist

- [x] I searched existing issues and the [Roadmap](https://github.com/AprilNEA/OpenLogi#roadmap), and this isn't already tracked.

### Problem / motivation

I am using Windows 11 Pro with the Logitech MX Keys S keyboard. I modified the configuration of an F-key in the keys menu, but unfortunately, there is no button to reset it to default.

### Proposed solution

After an F-button is clicked, a button with the text "Reset to default settings" should appear below the F5 scroll window.

### Alternatives considered

In the Logi+ software, there is a button in the settings to reset all keyboard settings to their default values.

### Related area(s)

- [x] GUI
- [ ] CLI
- [x] Button actions / remapping
- [ ] DPI
- [ ] SmartShift
- [ ] Per-application profiles
- [ ] Configuration (TOML)
- [ ] Auto-update
- [ ] Other

### Additional context

Start in the GUI's F-key configuration screen and trace the existing F-key remapping action. Add a visible “Reset to default settings” action for the selected F-key below the F5 scroll window, then manually verify that it restores the default binding.

Written by the indexing model from the issue text.