Photos live on disk as photos/<board_key>/<file>.{jpg,jpeg,png} (a read-only
volume). A cached directory index (60s TTL) attaches a `photos` URL list to each
surface in /api/map; a /photos StaticFiles mount serves the files. Photos are
public — shown to anonymous visitors and managers alike.
The balloon renders a gallery (main image + thumbnail strip + "1 / N" counter);
clicking a thumbnail swaps the main image, and clicking the main image / "+N"
opens a fullscreen lightbox over the map (prev/next, Esc, backdrop close).
Surfaces without photos render exactly as before.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>