Refactor color management and UI components for consistency

- Updated color references in various widgets to use the new `opaquePrimary` color for better visual consistency.
- Refactored `ColorsManager` to improve color definitions and removed redundant color declarations.
- Enhanced UI elements across multiple dialogs and widgets to ensure a cohesive design language.

This change promotes maintainability and aligns with the updated color scheme.

lib/pages/routines/widgets/value_display.dart

@@ -19,13 +19,13 @@ class ValueDisplay extends StatelessWidget {
     return Container(
       padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 10),
       decoration: BoxDecoration(
-        color: ColorsManager.primaryColorWithOpacity.withOpacity(0.1),
+        color: ColorsManager.opaquePrimary.withOpacity(0.1),
         borderRadius: BorderRadius.circular(10),
       ),
       child: Text(
         '$label $unit ',
         style: context.textTheme.headlineMedium!.copyWith(
-          color: ColorsManager.primaryColorWithOpacity,
+          color: ColorsManager.opaquePrimary,
         ),
       ),
     );