FCM HTTP v1 requires Firebase service account JSON files.
Google shut down the old legacy FCM API (https://fcm.googleapis.com/fcm/send returns 404).

Download from Firebase Console for EACH project:

1. flyphone-employee (b2bemp push to employees)
   Firebase Console → flyphone-employee → Project settings → Service accounts
   → Generate new private key
   Save as: flyphone-employee-service-account.json  (in this folder)

2. flyphone-b2b (b2bapp push to customers)
   Firebase Console → flyphone-b2b → Project settings → Service accounts
   → Generate new private key
   Save as: flyphone-b2b-service-account.json  (in this folder)

Upload this entire firebase/ folder to live server:
  admin2_new/b2bapi/firebase/

After upload, forward cart push will work instantly on employee phones.
