Register exact TH-D75 identity and regional capabilities. Replace the fixed-offset D74/D75 FO and ME handling with bounded typed record codecs, and make shared Kenwood mode lookup preserve its unsupported sentinel within the declared table bounds.
Add malformed-input and round-trip codec coverage while leaving memory writes, arbitrary split, clone names, and asynchronous status unadvertised.
This data (I think) was part of multicast V1, and doesn't seem to be used any
more. Since neither V1 or V2 are enabled, there should be no external
conflicts.
See 'rigs/simplecat/SIMPLE_CAT_PROTOCOL.md' for the protocol spec.
Notes:
- Memory correctness checks were done using Valgrind.
- Tested with wsjtx-3.1.0_improved_PLUS_260228.tgz (with mods) and
Bunzee Labs' DDX HF Digital Transceiver
https://bunzee-labs.com/products/ddx
Tested on:
- Ubuntu Linux
- macOS Tahoe
- Windows 11
