cmd-tracksdb-copy-snaps-only

This CLI command creates a copy of a tracks.db database, but with the new db containing only the snaps bucket of the tracks. CatTracks APIs and the website depend on the availability of snaps for api.catonmap.info/snaps.

But the tracks.db is getting huge (355GB and counting). So I want to backup this old, swollen database, and re-init with a new one, but maintaining the functionality of the website.

Eventually I want to STOP SAVING the tracks in the "tracks" bucket of the database entirely, using only .json.gz files for persistent and general storage of tracks.