[FEATURE] Add German Language Support

Is your feature request related to a problem? Please describe.

German-speaking users cannot use the application in their native language, limiting the application's reach in German-speaking markets.

Describe the solution you'd like

Add complete German language support:

  1. Translation Implementation:
  • Create German translation files
  • Translate all UI elements and messages
  • Implement German-specific formatting (dates, numbers, etc.)
  • Add German language option to language selector

Describe alternatives you've considered

  1. Using automated translation services
  2. Partial translation of critical features only

Additional context

  • Depends on core i18n infrastructure implementation
  • Should follow the established translation file structure
  • Requires native German speaker review