* Fixed a race condition in `photo-carousel` where programmatic scrolling
(e.g., keyboard navigation) would conflict with `IntersectionObserver`
callbacks, causing the current photo to revert mid-scroll. Added an
`isProgrammaticScroll` flag to temporarily suppress observer updates
during these scrolls.
* Added explicit timeouts in `photo-gallery-test.gjs` to allow the carousel
animations to settle between keyboard events.
* Refactored `Modal` and `PhotoGallery` components to use `{{in-element}}`
to render their contents into a top-level `#modal-portal` div. This prevents
z-index and overflow clipping issues.
* Updated `index.html` to include the `#modal-portal` div.
