Accessibility: Themes with higher contrast

Both the light and the dark theme have rather low contrast, making it hard to read for some users. Adding high contrast versions or allowing the users to chose their own colors would alleviate this problem

No files, tests, or entry points are identified. Start by locating the Arduino IDE 1.x theme definitions and any accessibility-related UI tests, then clarify whether the intended outcome is high-contrast themes, user-selectable colors, or both; done requires an agreed design and verified readable contrast for light and dark themes.

Written by the indexing model from the issue text.