As a visitor, I want to switch the application language, so that I can use it in my preferred language.
Given I visit the application for the first time And my browser language is set to a supported language (English, German, Spanish, French, Dutch, or Turkish) Then the application automatically displays in my browser's language.
Given I visit the application for the first time And my browser language is not one of the supported languages Then the application defaults to English.
Given I am on any page Then a language selector is available in the navigation bar with: DE, EN, ES, FR, NL, TR.
Given I select a language from the selector Then all labels, messages, and UI elements update to the selected language.
Given I have selected a language Then my preference is stored in the browser (localStorage) And on subsequent visits my stored preference takes priority over browser language detection.