Function diff_schema 

pub fn diff_schema(
    method: &str,
    old_payload: &Value,
    new_payload: &Value,
) -> Vec<SchemaDiff>

Diff two schema payloads for a list method.

Compares named items (by their name field) and returns granular changes: added, removed, and modified items.

For methods without named items (e.g., initialize), returns a single “updated” diff if the payloads differ.