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/integration_test.rs

@@ -80,8 +80,10 @@ mod tests {
         let mut binder = Binder::new(globals.clone());
         let bound_ast = binder.bind(&ast).expect("Failed to bind");
 
-        // BRIDGE: Binder -> VM requires a TypedNode
-        let typed_ast = crate::ast::environment::dummy_type_check(bound_ast);
+        // Use the real TypeChecker instead of the dummy placeholder
+        let global_types = Rc::new(RefCell::new(std::collections::HashMap::new()));
+        let checker = crate::ast::compiler::TypeChecker::new(global_types);
+        let typed_ast = checker.check(bound_ast).expect("Type check failed");
 
         let vm_globals = Rc::new(RefCell::new(Vec::new()));
         let mut vm = VM::new(vm_globals);