Add tuple and map literals

This commit introduces support for tuple and map literals in the AST.
Tuples are now represented by `UntypedKind::Tuple` and maps by
`UntypedKind::Map`.
The `Binder` has been updated to correctly handle these new node types
and infer their types.
The `VM` now also supports evaluating tuple and map literals.

src/ast/compiler/bound_nodes.rs

@@ -51,6 +51,14 @@ pub enum BoundKind {
         exprs: Vec<Node<BoundKind, StaticType>>,
     },
 
+    // NEW
+    Tuple {
+        elements: Vec<Node<BoundKind, StaticType>>,
+    },
+    Map {
+        entries: Vec<(Node<BoundKind, StaticType>, Node<BoundKind, StaticType>)>,
+    },
+
     // Extension points (need to be adapted for bound nodes if they use variables)
     // For now, we assume extensions are self-contained or handled dynamically.
 }