Adapt subscription icon background to light and dark themes #60

Description

The background behind the subscription icon/avatar currently uses the same gray color in both light and dark themes.

This makes the component look visually inconsistent when the application theme changes. The icon container should adapt its background color according to the active theme.

Current Behavior

• The icon background remains gray regardless of the selected theme.
• The component does not fully adapt to light mode.
• Visual consistency with the design system is lost.

Expected Behavior

• The icon background should automatically adapt to the active theme.
• In dark mode, it should use the dark palette.
• In light mode, it should use an appropriate light background.
• The component should maintain sufficient contrast and visual consistency in both themes.

Acceptance Criteria

• Icon background changes according to the active theme.
• Light mode uses a dedicated light background.
• Dark mode preserves the current dark appearance or an improved equivalent.
• The component follows the application's design system.