Add scripts for reading, filtering and plotting data

[MichalSzandar]

main script reads data from specified .mat file, groups signal data into 23 trials, applies savitzky-golay filter and optionally plots FFT results and savitzky-golay filtered vs raw data comparisons

[Copilot]

Pull request overview

This PR adds a data processing pipeline for SSVEP (Steady-State Visual Evoked Potential) EEG analysis. It reads .mat files, groups signal data into trials, applies a Savitzky-Golay filter, performs FFT/SNR analysis, and optionally generates plots.

Changes:

• Adds a main pipeline script with CLI arguments for reading, filtering, and optionally plotting EEG data
• Implements FFT analysis with SNR computation and confidence intervals, plus associated plotting functions
• Introduces supporting modules for constants, data classes, data reading, filtering, and utilities

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
data/src/main.py	Main entry point orchestrating the pipeline
data/src/consts.py	Constants for sampling, filtering, SNR, and channel config
data/src/data_classes.py	Data classes for trial groups and trial info
data/src/data_reader.py	Reads .mat files and groups DIN markers into trials
data/src/filter.py	Applies Savitzky-Golay filter to all trial epochs
data/src/filter_plotter.py	Plots raw vs filtered time-domain and PSD comparisons
data/src/fft_analysis.py	FFT magnitude, SNR computation, and confidence intervals
data/src/fft_plotter.py	Plots single-trial FFT, grouped FFT, and SNR heatmap
data/src/utils.py	Utility functions for grouping/filtering trials
data/src/init.py	Empty init file

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