v0.8.0

Highlights

• Negative integer literals (-10). Previously a syntax error in expressions and property maps.
• openCypher orderability. ORDER BY now orders across types per the spec (null sorts last; strings before numbers).
• GraphProvider::expand_in. Optional targeted incoming-neighbour lookup so an incoming step is O(degree) instead of a whole-graph reverse-adjacency build; defaulted, so existing providers are unaffected.
• Cheaper binding rows. Rows are now backed by a small Vec rather than a HashMap, cutting allocations when a large scan materializes one row per node.