- compute_grid antimeridian / invalid-bbox checks
- download_s2_cloud_mask (SCL-based per-pixel mask)
- _seasonal_select per-quarter cloud fallback
- Per-scene try/except in generate()
- BigTIFF auto-promotion + files_dir exists() guard

Space is pinned to betaearth[generate]>=0.2.3 so the next sync rebuild
pulls these in.