Mix Tasks
Post-process a mix firmware .fw so it ships the correct
user-merged initramfs/UBI rather than the system-only versions
baked in at system build time.
Ship the freshly-built firmware to a running OpenWRT One Nerves
device via the system's scripts/upload-ota.sh (volume-level
A/B-slot UBI OTA: writes the inactive fit_* UBI volume via
ubiupdatevol, flips nerves_fw_active via fw_setenv, reboots).