feat: Indigo updates for the Course Catalog MFE

[arbirali]

Description

This PR updates the Course Catalog MFE styling to align with the Indigo theme used across the Open edX platform.

The objective is to ensure visual consistency between the Course Catalog micro-frontend and the LMS when the Indigo theme is applied. The changes focus purely on styling and presentation without modifying functional behavior.

Key Changes

• Updated color usage to match Indigo theme variables.
• Aligned typography with Indigo’s font scale and hierarchy.
• Adjusted spacing and layout to reflect Indigo design patterns.
• Updated course card styles to maintain consistency with LMS components.
• Ensured button styles and interactive elements follow Indigo standards.
• Maintained responsiveness across breakpoints.
• Verified compatibility with existing Paragon components.

Before

Dark	Light

After

Dark	Light