Complete Phase 6.1: AST lowering for New/FieldAccess → MIR Ref ops with tests and VM field storage

Co-authored-by: moe-charm <217100418+moe-charm@users.noreply.github.com>

src/lib.rs

@@ -35,6 +35,9 @@ pub mod transport;
 // 🚀 MIR (Mid-level Intermediate Representation) Infrastructure (NEW!)
 pub mod mir;
 
+// 🚀 Backend Infrastructure (NEW!)
+pub mod backend;
+
 #[cfg(target_arch = "wasm32")]
 pub mod wasm_test;