Complete StructuredData parity and parser hardening (#37)

crates/libremetaverse-structured-data/src/model.rs

@@ -688,6 +688,9 @@ impl OSD {
     }
 }
 
+/// Format-neutral parser/serializer namespace matching the C# static type.
+pub struct OSDParser;
+
 macro_rules! scalar_wrapper {
     ($name:ident, $value:ty, $variant:ident, $kind:ident) => {
         #[derive(Clone, Debug)]