- Removed AppColors class and migrated all references to AppPalette.
- Updated VaultAccessScreen, MenuDrawer, NoteCard, SearchAppBar, and other widgets to use AppPalette for color management.
- Introduced AppPalette to handle light and dark themes with appropriate color schemes.
- Adjusted theme application in AppTheme to utilize AppPalette extensions.
- Updated tests to reflect changes in theme structure and color references.
