- pre-scan the GGUF metadata KV section and reject values gguf-parser-go would panic on, recurse on without bound, or overallocate for: wrong typed well-known keys, zero alignment, nested or oversized fully decoded arrays, an unreasonable `split.tensors.count`, and empty strings the parser would misread. Keys are matched the way the parser sees them. The KV count, fully read string bytes, and skipped string counts are bounded too. The file becomes an unknown instead of taking down the scan.
- `copyHeader` now bounds its own read to the max header size.
- non-finite floats in `header` (including inside arrays) become `"NaN"`, `"+Inf"` or `"-Inf"` so JSON encoding can't fail. `header` and `metadataHash` are otherwise unchanged.
- a `metadataHash` failure is now an error instead of an empty hash.
Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>