Implement Spectrum Visualiser #38
Description
A spectrum visualiser would enhance the usability of the project by providing a real-time graphical representation of audio frequencies. This feature should process the audio signal, compute the frequency spectrum (e.g., using FFT), and display it in a visually appealing way (such as a bar graph or waveform). Consider integration with the existing audio pipeline, update the UI to include the visualiser, and ensure performance is acceptable for real-time analysis. Add configuration options for the visualiser (e.g., color scheme, resolution, type of graph).