chore(i18n): update German translations for de_DE locale (#3884)

# Description of Changes

- **What was changed**  
- Updated `messages_de_DE.properties` to correct spacing in prompts
(e.g., changed `PDFs auswählen(2+)` to `PDFs auswählen (2+)`).
- Translated numerous English strings (error messages, prompts, UI
labels) into German.
- Standardized punctuation, grammar, and terminology across the German
locale.
- Fixed minor typos and formatting issues (e.g., “Stampelbild” →
“Stempelbild”, pipeline scan help, audit dashboard labels).

---

## 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/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/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/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/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

scripts/ignore_translation.toml

@@ -240,6 +240,12 @@ ignore = [
     'validateSignature.cert.version',
     'validateSignature.status',
     'watermark.type.1',
+    'audit.dashboard.tab.export',
+    'audit.dashboard.status',
+    'audit.dashboard.tab.dashboard',
+    'audit.dashboard.table.id',
+    'audit.dashboard.table.details',
+    'audit.dashboard.modal.id',
 ]
 
 [el_GR]