Flatpak crash on startup: KeyError 'Hoofdkleuren' (Dutch locale issue)

[megaflow8]

Describe the bug

The Flatpak application crashes immediately on startup when the system language is set to Dutch. It seems the application is trying to look up translated UI strings (like 'Hoofdkleuren') inside a color dictionary where only English keys exist.

How to reproduce

1. Set the system locale/language to Dutch (nl_BE / nl_NL).
2. Install Rewaita via Flatpak: flatpak install io.github.swordpuffin.rewaita
3. Launch the application: flatpak run io.github.swordpuffin.rewaita
4. The application crashes instantly with a Python Traceback.

Expected behavior

The application should open without crashing, even if the system language is set to Dutch.

Terminal Output / Traceback

Traceback (most recent call last):
  File "/app/share/rewaita/rewaita/main.py", line 156, in do_command_line
    win = RewaitaWindow(application=self)
  File "/app/share/rewaita/rewaita/window.py", line 107, in __init__
    self.custom_page = CustomPage(self)
                       ~~~~~~~~~~^^^^^^
  File "/app/share/rewaita/rewaita/custom_theme_page.py", line 136, in __init__
    self.append(CustomBundle(title, bundle))
                ~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/app/share/rewaita/rewaita/custom_theme_page.py", line 112, in __init__
    colors = gnome_colors[title.get_label()]
             ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
KeyError: 'Hoofdkleuren'

Context

• Installation Method: Flatpak (officially supported version)
• OS / Desktop Environment: Linux / GNOME
• Language/Locale: Dutch (Nederlands)

Additional Context / Verification

I have verified that this is 100% a locale issue.
When forcing the application to start in English using the following command, the app starts successfully without any crashes:

env LC_ALL=en_US.UTF-8 flatpak run io.github.swordpuffin.rewaita

[SwordPuffin]

This was an issue I thought I patched a while ago. I've fixed it again, maybe I cloned some old version to my computer and pushed it a second time.

The patch will be released as soon as #131 is resolved.

Thanks for reporting regardless.