Revamp advanced notebook with relevant examples and better demos

- Add DataLab introduction with link to datalab-platform.com
- Replace sinusoide with double-Gaussian peaks for FWHM demo
- Use Butterworth bandpass filter for log-scale example
- Add explicit ROI titles on multi-signal overlay
- Replace random noise with sine-wave pattern for non-uniform coords
- Add centroid overlay alongside enclosing circle in geometry demo
- Show per-ROI statistics and centroid in analysis results section

Author: PierreRaybaut