[Feat]: Add Carousel Counter Block

[theMasudRana]

Add Carousel Counter Block

Introduces a new carousel-kit/carousel-counter block that displays the current slide number and total slides
(e.g., "1 of 3").

Changes

• New block: src/blocks/carousel/counter/ with edit, save, index, and styles
• PHP registration: Added carousel/counter to block registration in Plugin.php
• Frontend interactivity: Added getCurrentSlideNumber and getTotalSlides callbacks in view.ts
• Types: Added CarouselCounterAttributes type export

Usage

The counter block can be inserted inside any Carousel block and automatically syncs with the carousel state via the shared Embla context.

Testing

1. Add a Carousel block to a page
2. Insert the "Carousel Counter" block inside the carousel
3. Verify counter updates when navigating slides (editor and frontend)