refactor: interpreter and type system improvements

- Parser and typechecker updates for new features
- Schema evolution refinements
- Type system enhancements

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/types.rs

@@ -1343,6 +1343,16 @@ impl TypeEnv {
                     Type::List(Box::new(Type::var())),
                 ),
             ),
+            (
+                "forEach".to_string(),
+                Type::function(
+                    vec![
+                        Type::List(Box::new(Type::var())),
+                        Type::function(vec![Type::var()], Type::Unit),
+                    ],
+                    Type::Unit,
+                ),
+            ),
         ]);
         env.bind("List", TypeScheme::mono(list_module_type));
 
@@ -1410,6 +1420,14 @@ impl TypeEnv {
                 "fromChar".to_string(),
                 Type::function(vec![Type::Char], Type::String),
             ),
+            (
+                "parseInt".to_string(),
+                Type::function(vec![Type::String], Type::Option(Box::new(Type::Int))),
+            ),
+            (
+                "parseFloat".to_string(),
+                Type::function(vec![Type::String], Type::Option(Box::new(Type::Float))),
+            ),
         ]);
         env.bind("String", TypeScheme::mono(string_module_type));