GalleryView wires the grid + timeline + modal together. The URL is the
source of truth for which image (if any) is open — clicking an item pushes
?image=N; closing the modal pops it. This makes deep links shareable and
the back button work intuitively.
Below 900px viewport, the timeline drops below the grid as a horizontal
strip so it doesn't compete with thumbnail space on mobile.
Modal store + ImageViewer are placeholders here; real implementations land
in Batch 5 (Tasks 19–22).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen