Set language parameter if it does not exist

setlangparameter.js

// Only proceed if we're not on a register page
if (!window.location.pathname.includes('/register')) {
  const params = new URLSearchParams(window.location.search);
  
  // Only add language param if it doesn't exist
  if (!params.has('language')) {
    params.append('language', 'en');
    
    // Construct new URL with updated params
    const newUrl = window.location.pathname + '?' + params.toString() + window.location.hash;
    window.history.replaceState(null, '', newUrl);
  }
}