feat(types): add TypeScript type definitions

## Summary Adds TypeScript type definitions for @microlink/cards package. ## Changes - Added `src/index.d.ts` with full type definitions for the microlinkCards function - Added `types` field to package.json pointing to the new type definition file ## Motivation This package previously had no TypeScript type definitions, making it difficult for TypeScript users to use @microlink/cards in their projects. These types provide full type safety and IDE autocompletion. ---