Feat/dark mode chart colors

[theFirstCodeManiac]

Closes #589

Description

This PR implements theme-aware chart colors for all Recharts components, ensuring proper visibility and consistency across both dark and light modes. It removes hardcoded color values and introduces a dynamic system that responds instantly to theme changes.

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Type of Change

• New feature (non-breaking change which adds functionality)
• UI/UX improvement
• Code refactoring
• Test coverage improvement

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Changes Made

• Created useChartColors hook to provide theme-based color palettes
• Implemented ChartThemeProvider for centralized color management
• Replaced all hardcoded chart colors with dynamic values from the hook
• Added MutationObserver to detect and respond to theme changes in real-time
• Ensured visual consistency with design system in both dark and light modes
• Added unit tests for theme color validation

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Testing

• Verified charts render correctly in both dark and light modes
• Confirmed instant updates on theme toggle without reload
• Added tests for color values across themes
• All tests pass with >90% coverage

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Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code where necessary
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my feature works
• New and existing unit tests pass locally

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Screenshots (if applicable)

N/A

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Additional Notes

This implementation ensures charts remain accessible, visually consistent, and fully responsive to theme changes without introducing performance overhead.

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