chore: massive repo reorganization

README.md

@@ -0,0 +1,33 @@
+# DongLoRa Firmware
+
+Embedded Rust firmware for DongLoRa boards. Exposes the LoRa radio over
+USB CDC-ACM using a COBS-framed binary protocol.
+
+## Building
+
+```sh
+just setup              # one-time toolchain install
+just build heltec_v4    # build for a specific board
+just flash heltec_v4    # build + flash
+just check-all          # compile-check all boards
+just clippy heltec_v4   # lint
+just test               # host-side protocol unit tests
+```
+
+All commands are run from the `firmware/` directory.
+
+## Supported Boards
+
+| Board | MCU | Radio | Target |
+|-------|-----|-------|--------|
+| Heltec V3 | ESP32-S3 | SX1262 | xtensa-esp32s3-none-elf |
+| Heltec V4 | ESP32-S3 | SX1262 | xtensa-esp32s3-none-elf |
+| RAK WisBlock 4631 | nRF52840 | SX1262 | thumbv7em-none-eabihf |
+
+## Adding a Board
+
+See [src/board/PORTING.md](src/board/PORTING.md).
+
+## Protocol
+
+See [PROTOCOL.md](PROTOCOL.md) for the complete wire format specification.