FontKey class abstract

FontKey (sealed class)

Represents a type-safe key for font families in the design system.

Purpose:

• Provides predefined font keys (primary, secondary) for common usage.
• Allows runtime custom font keys using FontKey.custom('myFont').
• Ensures type safety and reduces errors compared to raw strings.
• Works seamlessly with FontRegistry and FontHelper.

Usage:

// Predefined fonts
final primaryKey = FontKey.primary;
final secondaryKey = FontKey.secondary;

// Custom font key
final customKey = FontKey.custom('brandX');