Adds `filename` to pages, pointed to the WACZ file those files come
from, as well as depth, favIconUrl, and isSeed. Also adds an idempotent
migration to backfill this information for existing pages, and increases
the backend container's startupProbe time to 24 hours to give it sufficient
time to finish the migration.
---------
Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>
