🔍 QR Code Verification
Server validates: SECURITY_QR = SHA-256(ID_QR + SECRET_KEY)
or scan both at once
How it works: ID_QR = SHA-256(DocType + RefNo + ClientName).
Server verifies SECURITY_QR = SHA-256(ID_QR + SECRET_KEY).
Server verifies SECURITY_QR = SHA-256(ID_QR + SECRET_KEY).