Description

public/app_components/card_carousel.js was a ~35-line vanilla JS file loaded
via a <script type="module"> tag in the demo. It handled nav button clicks and
scroll-based indicator/button state updates through delegated listeners on
document.

This PR replaces it entirely with a pure Rust module using web_sys, following
the same pattern established in #21 (lock_scroll.js) and #26 (otp.js).

What changed

• Added app_crates/registry/src/hooks/use_card_carousel.rs — two delegated
  event listeners on document, registered once via a thread_local! singleton:
  • click: walks up from the click target to CardCarouselNavButton via
    closest(), identifies prev/next by DOM identity comparison against
    buttons[0], scrolls the track by one full clientWidth
  • scroll (capture phase): computes the current slide index from
    scrollLeft / clientWidth, syncs aria-current on indicator dots and
    aria-disabled on prev/next nav buttons
• Wired CardCarouselTrack to call use_card_carousel::init() under
  #[cfg(target_arch = "wasm32")] — same pattern as use_input_otp::init()
  in InputOTP
• Deleted public/app_components/card_carousel.js
• Removed the <script> tag from demo_card_carousel.rs
• Updated the registry snapshot (demo_card_carousel.md) and tree.md to
  remove the js: dependency entry

Validation

cargo build -p registry

cargo clippy -p registry -- -D warnings

Closes #27