Review round 1: size per-worker buffers off the largest actual window
instead of WindowSize^2 (avoids allocating ~200+ MiB per worker for
small/partial rasters), cap workers at 8 regardless of GOMAXPROCS, remove
partially-written outputs when a run fails, wrap input-open errors with
node/group context, guard checkGrids against a node with no inputs, and
clamp a non-positive WindowSize so raster.Windows can't loop forever.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>