Function stemPath

tests/fl/audio/detector/vocal_real_audio.hpp:184–189

Helper to build path

// Helper to build path
static fl::string stemPath(const char* name) {
    fl::string p;
    p.append(STEMS_DIR);
    p.append(name);
    return p;
}
static fl::string mixPath(const char* name) {
    fl::string p;
    p.append(MIXES_DIR);