peff_uniprot_fetcher: Fetch UniProt protein data and generate PEFF (PSI Extended FASTA Format) files

peff_uniprot_fetcher generates PEFF (PSI Extended FASTA Format) files from the UniProt REST API. It fetches protein sequences and GFF annotations (natural variants, PTMs, processed forms) and writes them as annotated PEFF using pefftacular, with modification mapping backed by psimodpy, unimodpy, and uniprotptmpy. It requires Python 3.12 or later.