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/dialog_footer.dart

@@ -37,9 +37,7 @@ class DialogFooter extends StatelessWidget {
             DialogFooterButton(
               text: 'Confirm',
               onTap: onConfirm,
-              textColor: isConfirmEnabled
-                  ? ColorsManager.primaryColorWithOpacity
-                  : Colors.red,
+              textColor: isConfirmEnabled ? ColorsManager.opaquePrimary : Colors.red,
             ),
           ],
         ],
@@ -65,7 +63,7 @@ class DialogFooterButton extends StatelessWidget {
     return Expanded(
       child: TextButton(
         style: TextButton.styleFrom(
-          foregroundColor: ColorsManager.primaryColorWithOpacity,
+          foregroundColor: ColorsManager.opaquePrimary,
           disabledForegroundColor: ColorsManager.primaryColor,
         ),
         onPressed: onTap,