calcofi_dic — CF NetCDF releases

Versioning. Paths are named for the database release so a URL always answers "which release is this?". When a build is byte-identical to an earlier release the bytes are NOT duplicated — the release still gets a manifest and page, and the download points at the existing object. latest.txt holds the newest release.

CF scope. Fully CF: each row is an independent observation with its own time and position, which is a CF point collection. Rows are at the OCCURRENCE grain (event x taxon x life stage x depth), not the event grain, so a sample with many taxa contributes many points.