nemoR 0.99.3

New package development

• Added helpers for discovering open NeMO portal metadata, including species, platforms, modalities, assays, brain regions, file formats, data types, access types, studies, and labs.
• Added file search and manifest workflows for planning reproducible downloads from the NeMO Data Portal and Assets API.
• Added guarded download helpers that write manifest files with local paths, download status, checksums, query parameters, and retrieval metadata.
• Added first-pass loading helpers for compatible downloaded H5AD and 10x HDF5 files into SingleCellExperiment and optional Seurat workflows.
• Added package vignettes for exploration, manifest planning, download testing, and loading.