fix: use environment variable for API URL in carrier accept/reject pages

Replace hardcoded localhost:4000 URLs with NEXT_PUBLIC_API_URL environment variable
in carrier portal pages to support different environments (dev/staging/production).

Pages updated:
- app/carrier/accept/[token]/page.tsx
- app/carrier/reject/[token]/page.tsx

This fixes the issue where preprod environment (app.preprod.xpeditis.com) was calling
localhost:4000 instead of the correct API endpoint (api.preprod.xpeditis.com).

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/frontend/app/carrier/accept/[token]/page.tsx

@@ -32,7 +32,8 @@ export default function CarrierAcceptPage() {
 
       try {
         // Appeler l'API backend pour accepter le booking
-        const response = await fetch(`http://localhost:4000/api/v1/csv-booking-actions/accept/${token}`, {
+        const apiUrl = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000';
+        const response = await fetch(`${apiUrl}/api/v1/csv-booking-actions/accept/${token}`, {
           method: 'GET',
           headers: {
             'Content-Type': 'application/json',

apps/frontend/app/carrier/reject/[token]/page.tsx

@@ -32,7 +32,8 @@ export default function CarrierRejectPage() {
 
       try {
         // Appeler l'API backend pour refuser le booking
-        const response = await fetch(`http://localhost:4000/api/v1/csv-booking-actions/reject/${token}`, {
+        const apiUrl = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000';
+        const response = await fetch(`${apiUrl}/api/v1/csv-booking-actions/reject/${token}`, {
           method: 'GET',
           headers: {
             'Content-Type': 'application/json',