Add Feature: Trend background screen colour algorithm

[summercms]

Enhancement idea

• Add Feature: Trend background screen colour algorithm.
• Connect to Short and Medium Trend algorithms.
• Add menu options.
• Light and dark mode themes.
• Update the doc's.

Description

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Links

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[summercms]

Further tests needed to see if connect to short-term and medium-term themes <<<<<<<<

[summercms]

Going to connect this to themes <<<<<<<<