#[lua_userdata_methods]Expand description
Walks the methods of an impl T { ... } block and, for each one
tagged with a helper attribute (#[lua_method("name")] etc.),
emits the corresponding UserdataMethods builder call inside a
hidden __luna_userdata_register associated fn.
The UserdataMethods trait lives in
::luna_core::vm::UserdataMethods — the emitted code references it
by absolute path so the derive works for pure luna-core embedders
too. The intra-doc-link form is omitted because this proc-macro
crate cannot see luna_core in its cargo doc scope.
The original impl block is re-emitted unchanged (minus the helper attributes themselves), so the named fns are still directly callable from Rust.