v1.0.21

Fix firmware update not taking effect on nodes installed before v1.0.19

Bug: Nodes installed between v1.0.7 and v1.0.18 have systemd service files pointing to /usr/local/bin/ble_feeder and /usr/local/bin/wifi_feeder. The droneaware update command was copying new binaries to /opt/droneaware/ only, so services restarted the old binary from /usr/local/bin/. The version file updated (making droneaware status show the new version) but heartbeats still reported the old fw_version.

Fix: droneaware update now symlinks /usr/local/bin/ble_feeder and /usr/local/bin/wifi_feeder → /opt/droneaware/ after installing. Self-heals the path mismatch on first run — no manual service file editing needed.

All users stuck on old fw_version despite running droneaware update should run it once more to pick up this fix.