LoadPredictsData: Load (or download) PREDICTS data to a user-specified RDS file.
Description
Implements a simple file-based cache. You supply a target filename
(e.g. "data/predicts_2016_2022.rds"). The function will:
Look for that RDS file and the companion metadata file
"filename.aux.json" (e.g. "data/predicts_2016_2022.rds.aux.json").
If both exist, verify the file hash, minimal structure, and requested
years.
If validation passes return the loaded object.
Otherwise download fresh data via GetPredictsData(extract), overwrite
the RDS, write a new .aux.json, and return the dataframe.
The data are provided under a CC NC (non-commercial) license, which means
that they cannot be used for commercial purposes. The 2016 release is
available under a CC BY-NC-SA 4.0 license, and the 2022 release is available
under a CC NC (any) license.