Fix recursive input event loop causing stack overflow in ColorPickerSlider

[Rakosn1cek]

Description of Changes

Interacting with the colour picker wheel or slider resulted in an immediate crash due to stack overflow.

When updating colours programmatically, ColorPickerSlider.Color calls Gtk.Entry.SetText(). Under GTK4, setting text fires the OnInputFieldChanged signal even when the entry is not being actively focused or edited by the user. This re-invoked OnColorChanged, updating ColorPickerDialog, which then assigned back to Color in an infinite recursion.

This patch introduces a suppress_input_events guard to ignore input change notifications during programmatic text updates in both the Color setter and slider drag handlers, preventing the feedback loop.

Checklist

• This pull request follows the project's contribution guidelines