refactor: string colors to themes

[tuliomir]

While investigating incorrect colors for the application on #326 , all the application existing UI colors were mapped.

This PR refactors all hardcoded colors spread throughout the code into the centralized theme constants. This will allow for easier future development of configurable themes and dark mode.

Acceptance Criteria

• UI colors should use themes.js constants instead of harcoded strings

ℹ️ Changed colors
Some hardcoded colors were slightly off the mapped ones and were adjusted to the nearest available. These cases were highlighted in the comments below for easier review.

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.