feat: add French and Spanish locales and update language selector

client/src/utils/i18nLanguages.ts

@@ -2,7 +2,7 @@ import type { i18n as I18nInstance } from 'i18next'
 import { PlausibleEvents, trackPlausibleEvent } from '../services/analytics.js'
 
 /** Supported UI languages (ISO 639-1, language-only). */
-export const SUPPORTED_LANGUAGES = ['de', 'en', 'da', 'sv', 'nb'] as const
+export const SUPPORTED_LANGUAGES = ['de', 'en', 'da', 'sv', 'nb', 'fr', 'es'] as const
 
 export type AppLanguage = (typeof SUPPORTED_LANGUAGES)[number]
 
@@ -11,7 +11,9 @@ export const LANGUAGE_FLAGS: Record<AppLanguage, string> = {
   en: '🇬🇧',
   da: '🇩🇰',
   sv: '🇸🇪',
-  nb: '🇳🇴'
+  nb: '🇳🇴',
+  fr: '🇫🇷',
+  es: '🇪🇸'
 }
 
 export function normalizeAppLanguage(language?: string): AppLanguage {