void cqt_forward(
[]const double signal,
double fs,
double fmin,
unsigned long binsPerOctave,
[]Complex out,
)'signal' must have at least enough samples for the lowest bin's (longest) kernel — roughly Q*fs/fmin samples, Q = 1/(2^(1/binsPerOctave)-1) — or that bin's kernel is silently clipped to signalLen (a degraded, not incorrect, result: still valid, just with worse frequency resolution than requested for that bin). 'out' must have room for 'numBins' Complex values.