By: Michael Lynch <git@mtlynch.io>
Replace index page with media browse grid
The index page now shows a 4-column Bootstrap 5 grid of square
thumbnails, each linking to /media/{uuid}. Thumbnails are served
from a configurable --media-dir flag (defaults to data/media).
The visit counter UI is removed from the page; the visits
store and /api/visits route remain for now.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>