The host-side build/verify/inspect/serve CLI now lives as a standalone Rust
project at https://github.com/vk496/motatool. Remove the in-tree C++ copy
(tools/motatool/) and repoint the docs (ota_protocol.md, ota_user_guide.md,
tools/mota/README.md) at the standalone repo.
No cross-dependency either direction: MeshCore's firmware build never invoked
motatool (only tools/mota/ Python glue runs in the build), and motatool depends
only on the shared .mota wire spec in docs/ota_protocol.md. tools/mota/
(pio_endf.py EndF hook, motalib.py reference lib, gen_targets.py) is unchanged.