Add five new sqlc queries to support the series browse page and
continue-series dashboard collection:
- GetDistinctSeries: list unique series with book counts, sorted by
most recent entry, with pagination
- GetDistinctSeriesCount: total distinct series count for pagination
- GetSeriesCovers: fetch up to N cover image paths for a series,
ordered by series_number
- GetSeriesBooks: fetch all books in a series ordered by series_number
- GetContinueSeriesItems: CTE-based query using DISTINCT ON to find
the next unread book per series for a given user/library, sorted
by most recent last_read_at
john-okeefe
d48404e800