Chart functions clutter main program app.py. Move and refactor.

1. move charts from app.py to charts.py
2. refactor charts
3. create well defined adn documented sections for charts and each

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4. create a chart class and initialze each chart as an instance of a main chart Class.

Start by reading app.py to identify the chart functions and how they are used. Move the chart-related work into charts.py, then define documented chart sections and a main chart class whose instances represent each chart. Done means app.py no longer contains the chart implementations and the refactored chart structure is clear.

Written by the indexing model from the issue text.