pub const KIND_HNSW: u8 = 0x05;Expand description
Phase 7d.3: a single HNSW node’s per-layer neighbor lists,
serialized into one cell. Body layout (after the shared
cell_length | kind_tag prefix):
node_id zigzag varint the rowid this graph node represents
max_layer varint highest layer this node lives in
for each layer 0..=max_layer:
count varint number of neighbors at this layer
for each: zigzag varint neighbor node_idpeek_rowid works uniformly on this kind because it just reads
the first varint after the kind tag — exactly the node_id here.