Saved language setting is ignored on application startup

### Is there an existing issue for this?

- [x] I searched the existing issues and did not find anything similar.

### Current Behavior

The selected application language is not applied when AntiMicroX starts.
I changed the application language to German in:
Options → Settings → Language

The setting is saved correctly in:

`~/.var/app/io.github.antimicrox.antimicrox/config/antimicrox/antimicrox_settings.ini`

The file contains:

`language=de`

However, after closing and restarting AntiMicroX, the application starts in English again.

The Flatpak environment also reports:

`LANG=de_DE.UTF-8`

If I open the Language window and simply press OK without changing anything, AntiMicroX immediately switches to German. After restarting the application, however, it is English again.

### Expected Behavior

The selected language should be loaded and applied automatically when AntiMicroX starts.

### Steps To Reproduce

1. Install AntiMicroX from Flathub.
2. Start AntiMicroX.
3. Go to Options → Settings → Language.
4. Select German as the application language.
5. Press OK.
6. Close AntiMicroX completely.
7. Start AntiMicroX again.
8. The application starts in English instead of German.
9. Open Preferences and press OK.
10. The application immediately switches to German.

### Environment

```markdown
Program Version 3.6.1
Compiled from packaging: flatpak
Built Against SDL 2.32.66
Running With SDL 2.32.70
Using Qt 6.10.3
Using Event Handler: uinput
Compositor type: wayland
Host OS: org.kde.Platform Version: 6.10 Architecture: x86_64
```

### Anything else?

_No response_

Start with the antimicrox_settings.ini setting and trace the application startup path that should read it, then compare it with the Options → Settings → Language OK path that applies German immediately. Done means language=de is applied after a fresh restart without reopening the language window; check for an existing regression-test entry point if the project provides one.

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