fix(interface): preserve operation item uniqueness

Disambiguate generated argument types when distinct operation names normalize to the same PascalCase form, and add the requested Number round-trip and collision regression coverage.

crates/wip-interface/tests/codecs.rs

@@ -67,6 +67,17 @@ fn supported_values_round_trip() {
     assert!(fields.iter().all(|field| field.name != "priority"));
     assert_eq!(Request::decode(encoded).unwrap(), request);
 
+    let number = 42.5_f64;
+    assert_eq!(f64::type_expr(), TypeExpr::Number);
+    assert_eq!(f64::decode(number.encode().unwrap()).unwrap(), number);
+
+    let narrow_number = 1.5_f32;
+    assert_eq!(f32::type_expr(), TypeExpr::Number);
+    assert_eq!(
+        f32::decode(narrow_number.encode().unwrap()).unwrap(),
+        narrow_number
+    );
+
     for color in [Color::Red, Color::Blue] {
         let encoded = color.clone().encode().unwrap();
         let decoded = Color::decode(encoded).unwrap();