feat: Add type checking to the compiler

Introduces the `TypeChecker` struct and its associated `TypeContext` for
performing static type analysis on the abstract syntax tree.

This change includes:
- A new `type_checker.rs` module.
- Integration of `TypeChecker` into the `Environment::compile` method.
- Updates to `Environment` to manage global types.
- Renaming `bound_nodes.rs`'s `BoundNode` to `TypedNode` to reflect its
  type-checked nature.
- Refinements in binder and macro expansion to accommodate type
  information.

src/ast/compiler/bound_nodes.rs

@@ -80,7 +80,7 @@ pub enum BoundKind<T = ()> {
     },
 
     Map {
-        entries: Vec<(Node<BoundKind<T>, T>, Node<BoundKind<T>, T>)>,
+        entries: Vec<MapEntry<T>>,
     },
 
     /// An expanded macro call, preserving the original call for debugging and UI.
@@ -95,6 +95,9 @@ pub enum BoundKind<T = ()> {
     Extension(Box<dyn BoundExtension<T>>),
 }
 
+/// A single entry in a Map literal (Key-Value pair)
+pub type MapEntry<T> = (Node<BoundKind<T>, T>, Node<BoundKind<T>, T>);
+
 /// Type alias for a node that has been bound (addresses resolved) but not yet type-checked.
 pub type BoundNode = Node<BoundKind<()>, ()>;