fix(format): a v1 group with an empty link name fails its listing

libhdf5 refuses to list a symbol-table group that has an entry with an
empty name (H5G__ent_to_link: "invalid link name"), so h5py cannot list
cve-2021-46244's /BAG_root. We listed it, with an object at "/BAG_root/"
(the empty name, pointing at address 0). resolve_v1_group_entries — the
listing — now fails with the new FormatError::InvalidLinkName; path
lookups still find the group's other names, as libhdf5's by-name lookup
does.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

crates/clawhdf5-format/src/group_v2.rs

@@ -450,7 +450,9 @@ fn resolve_group_entries(
             .find(|m| m.msg_type == MessageType::SymbolTable)
             .ok_or_else(|| FormatError::PathNotFound(String::from("no symbol table message")))?;
         let stm = SymbolTableMessage::parse(&sym_msg.data, offset_size)?;
-        group_v1::resolve_v1_group_entries(file_data, &stm, offset_size, length_size)
+        // A lookup: an entry with an empty name (which fails a listing) is
+        // skipped by the name comparison, as in libhdf5.
+        group_v1::v1_group_entries(file_data, &stm, offset_size, length_size)
     } else if is_v2_group(object_header) {
         resolve_v2_group_entries(file_data, object_header, offset_size, length_size)
     } else {