Task/improve language localization for DE (20260731) (#7479)

* Add translations

* Update changelog

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Changed
+
+- Improved the language localization for German (`de`)
+
 ## 3.37.0 - 2026-07-30
 
 ### Added

apps/client/src/locales/messages.de.xlf

@@ -351,7 +351,7 @@
       </trans-unit>
       <trans-unit id="4467323362722952678" datatype="html">
         <source>Unknown</source>
-        <target state="new">Unknown</target>
+        <target state="translated">Unbekannt</target>
         <context-group purpose="location">
           <context context-type="sourcefile">libs/ui/src/lib/i18n.ts</context>
           <context context-type="linenumber">88</context>
@@ -1767,7 +1767,7 @@
       </trans-unit>
       <trans-unit id="659291745893337969" datatype="html">
         <source>Invalid API key</source>
-        <target state="new">Invalid API key</target>
+        <target state="translated">Ungültiger API-Schlüssel</target>
         <context-group purpose="location">
           <context context-type="sourcefile">apps/client/src/app/components/admin-settings/admin-settings.component.html</context>
           <context context-type="linenumber">112</context>