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/analytics/modules/air_quality/widgets/aqi_gauge.dart

@@ -65,7 +65,7 @@ class AqiGauge extends StatelessWidget {
         pointer: GaugePointer.circle(
           position: const GaugePointerPosition.surface(),
           radius: MediaQuery.sizeOf(context).width * 0.004,
-          color: ColorsManager.whiteColors,
+          color: ColorsManager.white,
           border: GaugePointerBorder(
             width: 6,
             color: statusColor,