v0.39.4

Fixed — reindex read the catalogue, so it could not repair the catalogue

The repair path for 0.39.3 did not work. rtfm reindex selects the files to
re-ingest from books — but a book deleted by the reconcile pass leaves only
its tracking row behind, and that is precisely the state a re-ingest exists to
fix. It answered "no matching indexed files" for all 5 738 HTML documents the
fleet had lost that way.

It now reads indexed_files, which is the authority on what is indexed at a
path, and whose filepath is a relative path by definition —
books.filename is not reliably one, holding a bare basename in some
projects, which the root lookup then failed to resolve.