Currently RADE is disabled on Windows (ENABLE_RADE=OFF) because the bundled Opus build uses autotools which isn't available on Windows CI runners.

Windows users who want RADE need a way to build radae_nopy separately (it has its own CMakeLists.txt that works with MSVC) and point AetherSDR at the installed library.

Proposed solution: Add a hybrid detection path in CMakeLists.txt:

1. First try find_library(RADE_LIB rade) / find_path(RADE_INC rade_api.h) for a system-installed RADE
2. If not found and ENABLE_RADE=ON, fall back to the bundled ExternalProject build (Linux/macOS only)

This would let Windows users build RADE from source, install it, and rebuild AetherSDR with -DENABLE_RADE=ON to pick it up automatically.