📡 Optical link demo

Transmit text by blinking a phone screen, receive it with a laptop webcam.

📱 Sender (phone) 📷 Receiver (laptop) ⬇ Sender (single file, AirDrop to phone)

Receiver must be opened on the laptop via http://localhost:8000/receive (so the browser allows camera access).
Sender can be opened on the phone either via http://<laptop-ip>:8000/send, or — if the Wi-Fi blocks device-to-device connections — download the single-file sender on the laptop, AirDrop it to the phone, and open it there (it needs no network).