ota: extract the motatool CLI to its own repo (github.com/vk496/motatool)

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.

docs/ota_protocol.md

@@ -33,7 +33,7 @@ where a section names a source file, that file is the authoritative reference fo
 | Staging stores | `OtaStore.h`, `OtaStoreFlashNrf52.*`, `OtaStoreFlashEsp32.*` |
 | Apply | `OtaApply.*`, bootloader `Adafruit_nRF52_Bootloader_OTAFIX` |
 | Device glue (CLI/context) | `OtaCli.cpp`, `OtaContext.h` |
-| Host tooling | `tools/motatool/` (C++ CLI: build/verify/inspect/serve); `tools/mota/` (Python reference lib `motalib.py` + build/test glue) |
+| Host tooling | [`motatool`](https://github.com/vk496/motatool) (standalone Rust CLI: build/verify/inspect/serve); `tools/mota/` (Python reference lib `motalib.py` + build/test glue) |
 
 ---
 
@@ -540,8 +540,8 @@ blocks) and streams payload blocks from the source on demand; proofs are generat
 
 A `MotaSource` is fed by a host that serves a folder over the device's **USB serial** (the same console the
 CLI uses — no extra hardware) or, on an ESP32 WiFi companion, over **WiFi (TCP)**. The host is the
-self-contained C++ tool `tools/motatool/` (`motatool serve --serial <port>` / `--tcp <host[:port]>`, which
-also builds + validates `.mota` and runs on small hardware). The device only emits request frames *while
+standalone Rust tool [`motatool`](https://github.com/vk496/motatool) (`motatool serve --serial <port>` /
+`--tcp <host[:port]>`, which also builds + verifies + inspects `.mota`). The device only emits request frames *while
 actively serving a fetch*, and reads the reply synchronously, so over the shared USB console binary frames
 coexist with the text CLI/logs (resync on magic + checksum). Little-endian, XOR-checksummed:
 

docs/ota_user_guide.md

@@ -203,19 +203,20 @@ folder of firmware files to the mesh — without storing them itself. Useful for
 remote area.
 
 1. Put the firmware files (`.mota` files — see below) in a folder on the computer.
-2. Build the helper tool once (`tools/motatool/`), then point it at your node and the folder — over the
-   node's **USB serial**, or over **WiFi** if it's an ESP32 companion on your network:
+2. Install the helper tool once — the standalone `motatool` CLI (<https://github.com/vk496/motatool>) —
+   then point it at your node and the folder — over the node's **USB serial**, or over **WiFi** if it's
+   an ESP32 companion on your network:
    ```
-   cmake -S tools/motatool -B tools/motatool/build && cmake --build tools/motatool/build
+   git clone https://github.com/vk496/motatool && cargo install --path ./motatool
    # over USB serial:
-   ./tools/motatool/build/motatool serve --dir ./my_firmware/ --serial /dev/ttyACM0 -v
+   motatool serve --dir ./my_firmware/ --serial /dev/ttyACM0 -v
    # …or over WiFi (ESP32 companion): the seeder is on a DEDICATED port (5001), separate from the
    # phone-app port (5000), so a phone can stay connected while you serve:
-   ./tools/motatool/build/motatool serve --dir ./my_firmware/ --tcp 192.168.1.50:5001 -v
+   motatool serve --dir ./my_firmware/ --tcp 192.168.1.50:5001 -v
    ```
    It answers the node's requests; your node then advertises those updates to neighbours, who can
    `ota get` them like any other. (A WiFi node prints its IP + seeder port to the serial log on connect.
-   Details: [tools/motatool/README.md](../tools/motatool/README.md).)
+   Details: <https://github.com/vk496/motatool>.)
 
 To stop, just stop the daemon — over WiFi the node auto-detaches when the connection closes; over USB you
 can also run `ota folder off` on the node. `ota folder` on its own lists what your node is offering.