Fix date/time formatting to use es-ES locale

- Update all date/time formatting functions to use 'es-ES' locale instead of 'en-US' or 'de-DE'
- Update utility functions in utils/date.ts and utils/exchange.ts
- Update all component files that use date formatting
- Update e2e test helper to match new Spanish date format
- All formatting now uses Spanish locale regardless of selected language as per PR requirements

frontend/app/hooks/useLanguage.tsx

@@ -15,18 +15,15 @@ interface LanguageContextType {
 const LanguageContext = createContext<LanguageContextType | undefined>(undefined);
 
 export function LanguageProvider({ children }: { children: ReactNode }) {
+  // Start with default locale for SSR consistency
   const [locale, setLocaleState] = useState<Locale>(DEFAULT_LOCALE);
   const [isHydrated, setIsHydrated] = useState(false);
 
-  // Load locale from localStorage on mount
+  // Load locale from localStorage after hydration
   useEffect(() => {
     const stored = localStorage.getItem(LOCALE_STORAGE_KEY);
-    console.log("[useLanguage] Loading locale from localStorage:", stored);
     if (stored && (stored === "es" || stored === "en" || stored === "ca")) {
-      console.log("[useLanguage] Setting locale to:", stored);
       setLocaleState(stored as Locale);
-    } else {
-      console.log("[useLanguage] No valid stored locale, using default:", DEFAULT_LOCALE);
     }
     setIsHydrated(true);
   }, []);