Function execute 

pub fn execute(
    backend: &SqliteGraphBackend,
    query: &CypherQuery,
) -> Result<Value, String>

Execute a parsed CypherQuery against a SQLite-backed graph.

Returns a JSON object whose shape depends on the statement kind:

• Match: {"results": [...], "count": N}
• CreateNode / CreateEdge: {"id": <new_id>}
• Set: {"updated": N}
• Delete: {"deleted": N}

Errors

Returns an error if execution fails (parse-time errors are surfaced via parse).