GHSA-vv3m-f8x4-7377: lightrag-hku: SSRF via IPv6-transition address bypass (NAT64, IPv4-compatible, 6to4) of the native-markdown im

## Summary LightRAG's native markdown parser downloads external images referenced by an uploaded markdown or textpack document. The only SSRF guard, `_validated_addresses()` in `lightrag/parser/markdown/parser.py`, resolves the image host and rejects it when the resolved IP is not `is_global`. That check is evaluated on the raw resolved address and never decodes IPv6 transition wrappers that embed an internal IPv4. …