OpenCPN Climatology data bundle

This directory is self-contained for normal offline use.  A modern versioned
bundle includes dataset-manifest.json (machine readable) and
DATASET_PROVENANCE.md (human readable), which identify each source product,
actual per-variable period, processing method, generator revision and output
checksum.

These are historical planning climatologies, not forecasts.  The coarse depth
layer is contextual and must not be used for navigation.
