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/create_new_routines/space_dropdown.dart

@@ -35,8 +35,7 @@ class SpaceDropdown extends StatelessWidget {
           DropdownButton2<String>(
             underline: const SizedBox(),
             buttonStyleData: ButtonStyleData(
-              decoration:
-                  BoxDecoration(borderRadius: BorderRadius.circular(12)),
+              decoration: BoxDecoration(borderRadius: BorderRadius.circular(12)),
             ),
             value: selectedValue,
             items: spaces.map((space) {
@@ -98,9 +97,7 @@ class SpaceDropdown extends StatelessWidget {
                       padding: const EdgeInsets.only(left: 10),
                       child: Text(
                         selectedValue != null
-                            ? spaces
-                                .firstWhere((e) => e.uuid == selectedValue)
-                                .name
+                            ? spaces.firstWhere((e) => e.uuid == selectedValue).name
                             : hintMessage,
                         style: Theme.of(context).textTheme.bodySmall!.copyWith(
                               fontSize: 13,
@@ -134,7 +131,7 @@ class SpaceDropdown extends StatelessWidget {
             dropdownStyleData: DropdownStyleData(
               maxHeight: MediaQuery.of(context).size.height * 0.4,
               decoration: BoxDecoration(
-                color: ColorsManager.whiteColors,
+                color: ColorsManager.white,
                 borderRadius: BorderRadius.circular(10),
               ),
             ),