feat(i18n): add German translations (#4796)

# Description of Changes

This pull request makes minor improvements to the German localization
and translation management. The changes primarily update UI strings for
clarity and consistency and adjust the translation ignore list.

Localization improvements:

* Updated urgent update notification and related UI strings in
`messages_de_DE.properties` for better clarity and consistency.
* Improved analytics labels and translated "Scarf Pixel" to
"Schal-Pixel" in `messages_de_DE.properties`.

Translation management:

* Removed `scannerEffect.quality.medium` from the translation ignore
list in `ignore_translation.toml`.

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

scripts/ignore_translation.toml

@@ -240,7 +240,6 @@ ignore = [
     'pipelineOptions.pipelineHeader',
     'pro',
     'redact.zoom',
-    'scannerEffect.quality.medium',
     'sponsor',
     'team.status',
     'text',