After 2+ disconnects during provisioning, the beacon's BLE stack can
return incomplete characteristic discovery results. Instead of hard-
failing with "DX-Smart command characteristic (FFE2) not found", we
now re-trigger characteristic discovery (up to 2 attempts) and resume
writing from the saved position once FFE2 is found.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>