floats iter 1.1: Literal::Float variant + canonical hex serde + drift-test anchors

crates/ailang-codegen/src/lib.rs

@@ -925,6 +925,7 @@ impl<'a> Emitter<'a> {
                 let g = self.intern_string("str", value);
                 ("ptr".to_string(), format!("@{g}"))
             }
+            Literal::Float { .. } => unimplemented!("Floats milestone iter 4: codegen"),
         };
         if val_ty != lty {
             return Err(CodegenError::Internal(format!(
@@ -1224,6 +1225,7 @@ impl<'a> Emitter<'a> {
                     (format!("@{g}"), "ptr".into())
                 }
                 Literal::Unit => ("0".into(), "i8".into()),
+                Literal::Float { .. } => unimplemented!("Floats milestone iter 4: codegen"),
             }),
             Term::Var { name } => {
                 // Iter 16d: `__unreachable__` is a polymorphic bottom
@@ -2358,6 +2360,7 @@ impl<'a> Emitter<'a> {
                 Literal::Bool { .. } => Type::bool_(),
                 Literal::Str { .. } => Type::str_(),
                 Literal::Unit => Type::unit(),
+                Literal::Float { .. } => Type::float(),
             }),
             Term::Var { name } => {
                 // Lookup precedence: extras (let-bindings introduced