jsansao/s2nr — reverse-engineered prompt

Build me a simple MATLAB project for measuring spectrographic signal to noise ratio using the files in this repo. The README is basically empty, so please figure out the flow from the existing functions and make it easy for someone to run without digging through the code.

I want one clear entry point where I can give it a sample signal or spectrogram data, run the measurement, and get a clear SNR result back. If the existing code estimates frequency, normalises data, segments ridges, filters ridges, or measures the final score, wire those pieces together cleanly and add comments so it’s understandable.

Please also add a small demo with example data, basic plots showing the input and the detected or processed signal areas, and a short README that explains how to run it in MATLAB, what the inputs should look like, and what the output number means. Look up current MATLAB docs online if you need to.