feat(i18n): add language picker and 5-language support to all auth screens

- Add svelte-i18n and @manacore/shared-i18n to Chat, Presi, Zitare
- Create LanguageSelector component for each app
- Add locale files for DE, EN, IT, FR, ES in all apps
- Update auth pages (login, register, forgot-password) to use shared translations
- Add headerControls snippet to RegisterPage and ForgotPasswordPage
- Export ZitareLogo and NutriPhiLogo from shared-branding

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/shared-branding/src/index.ts

@@ -22,6 +22,8 @@ export {
 	UloadLogo,
 	ChatLogo,
 	PresiLogo,
+	NutriPhiLogo,
+	ZitareLogo,
 } from './logos';
 
 // Configuration