Rename classic ValueArgument.annotation to attributes

[DamianReeves]

Problem

ValueArgument in the classic IR names its value-attribute payload annotation:

crates/morphir-core/src/ir/classic/value.rs

That payload is the classic attribute type parameter (VA), the same slot a tagged value node carries and that v4 spells as attributes. The name annotation collides with the v4 annotations list, which is a different member. That list lives only on specifications and names fully qualified values. The classic field is not that list.

The classic JSON form is the positional tuple [name, payload, type]. The field name is not on the wire.

Change

Rename ValueArgument.annotation to ValueArgument.attributes.

Update the struct, its serializer and deserializer, and the constructors that set the field:

• crates/morphir-core/src/ir/classic/value.rs
• crates/morphir-python-binding/src/ir/classic.rs
• crates/morphir-mck-adapter/src/testee.rs
• crates/morphir-rust-binding/src/frontend/values.rs

Leave the serialized tuple unchanged. Do not rename v4 annotations, and do not rename Gleam or Python source-annotation fields that happen to use the same word.

Done when

Classic value parameters read attributes in Rust, and classic JSON fixtures still decode as [name, payload, type].