User-context code execution via unchecked receive paths

Path traversal in Linux Mint Warpinator 1.2.14 and earlier allows remote attackers to overwrite files outside the receive directory. The FileReceiver.receive_data method accepts a peer-controlled relative_path value and creates the resolved file without first verifying that it remains beneath the configured save path. An attacker who knows the group code can overwrite files writable by the Warpinator user after transfer approval; disabling approval makes exploitation unattended, and overwriting shell startup files grants code execution as that user.