Collection source:
- Collection list: don't default to @author as source label
- Collection detail: suppress SOURCE when it equals @author
- Collection detail: 'curated by' instead of 'authored by'
- No source shown when field is empty
Back button:
- isRouting guard on route() prevents showDetail, showCollectionDetail,
showUser, and navigate from setting location.hash when called from
a hashchange event (back button). This prevents duplicate history
entries that trap the user.
Home click:
- navigate('library') no longer blocked by currentRoute guard
(view !== 'library' exception), so clicking the site name always
returns to the homepage.