Improve tempo tracking: 100% detection rate with FFT autocorrelation, Fourier tempogram (debugging onset integration), dynamic tempo tracking, multi-octave detection, time-based test infrastructure, benchmarking, and Python bindings

Improve tempo tracking: 100% detection rate with FFT autocorrelation, Fourier tempogram (debugging onset integration), dynamic tempo tracking, multi-octave detection, time-based test infrastructure, benchmarking, and Python bindings #13