German (default) in values/strings.xml, English in values-en/strings.xml.
Matches web app's next-intl de/en setup.
Migrated: greeting, hero headline, chat input, error messages, mode pills,
suggestion pills, sidebar (brand, search, dates, logout, settings),
model sheet, login screen (welcome, fields, errors, submit button),
conversation labels (locked, pinned).
ChatModels: Suggestion/ChatMode now use resource IDs instead of hardcoded strings.
greeting() is now @Composable (uses stringResource).
ModePillsRow: selected state uses resource ID (Int) instead of String.
Date labels (HEUTE/GESTERN/FRÜHER) localized via DateLabels data class.