gdscript-hir — the semantic / type layer.
Lowers the AST to a HIR (an ItemTree of signatures + per-function Body), runs name resolution
(local → class member → inherited → global), gradual type inference (Variant by default,
:=/annotations, member lookup over the engine inheritance table, is/as narrowing), and the
GDScript warning checks. Single-file in Phase 2; project-wide + scene-aware later.
Phase 2 builds this out bottom-up: the type model ([ty]), then the item tree, body, name
resolution, and inference. Must build for wasm32.