Closes#11199
# Which Problems Are Solved
This PR refactors the login app to load allowed languages and the
default language directly from the Zitadel API equivalents
(`getGeneralSettings`), rather than relying on a hardcoded list. This
ensures that the available languages in the UI and the locale selection
logic match the instance's configuration.
# How the Problems Are Solved
- Fetches allowed languages server-side and passes them to the
LanguageSwitcher
- The NEXT_LOCALE cookie and Accept-Language headers are now strictly
validated against the API-provided allowed languages.
- Fallback: If a cookie requests an unsupported language, the system now
falls back to the API's defaultLanguage (instead of valid but
unconfigured defaults).
# Additional Changes
Helper: Added `getLanguage(code)` to map API language codes to display
names (utilizing Intl.DisplayNames if the code isn't in our static
mapping).
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Co-authored-by: Livio Spring <[email protected]>
ab0f045499