Improve german localization

[jonaslang1]

This pull request updates the German localization strings in Pearcleaner/Resources/Localizable.xcstrings to improve consistency, accuracy, and clarity. The changes focus on standardizing terminology for "App," "Cask," and related terms, refining technical vocabulary, and correcting minor translation errors.

Key terminology and consistency improvements:

• Standardized the translation of "App" and related terms throughout the UI, replacing older terms like "Programm" and "Anwendung" with "App" or "Apps" where appropriate. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
• Updated "Cask" and "Formula" related terms to use the correct technical vocabulary ("Cask," "Casks," "Formulae") instead of literal translations such as "Fass" or "Formeln." [1] [2] [3] [4] [5]
• Improved translation of "Badge" to "Kennzeichen" for notification overlays, ensuring clarity for German users. [1] [2]
• Refined technical terms such as "Bundle" instead of "Bündel" and clarified instructions for command-line usage and helper tools. [1] [2] [3] [4] [5]
• Added and improved translations for new and existing UI strings, including "Zuletzt geändert: %@" and corrected minor translation errors (e.g., "Schließen" instead of "Schliessen"). [1] [2] [3]

Other notable improvements:

• Enhanced clarity in user instructions and warnings, such as refining language for manual actions and backup recommendations. [1] [2] [3] [4] [5]

These updates ensure a more professional, consistent, and user-friendly experience for German-speaking users.

[jonaslang1]

Found that there was another pr (#480) from @admonstrator for german localization and merged it into my pr and resolved conflicts and removed changes to other languages.

[jonaslang1]

@alienator88 Off topic question: I wanted to work on a feature request, but stumbled upon signing problems and some missing modules e.g. Module map file '/Users/alin/GitHub/PearcleanerGH/Pearcleaner/Logic/AppsUpdater/PrivateFrameworks/CommerceKit/module.modulemap' not found while trying to build and test.
Is there a contribution guide for this specific repo or can you give me some instructions how to work on this project.
Thank you in advance! Your project is awesome! 👏