fix: cap snapshot node count relative to file size
The 64x decompressed-body limit still let an 804 KB crafted snapshot
(repeating blocks of records) expand to 4.2 M nodes and ~500 MB of
heap, ~600x amplification; larger files exhaust memory. LoadFile now
allows at most one node per byte of file (1 Mi floor); real snapshots
use ~15 bytes per node. Limit errors on the node count are no longer
misreported as "no root node".
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Andy DixonandClaude Opus 5.5
b009ac3cbf