Function normalize_json_contract_arg 

fn normalize_json_contract_arg(arg: &str) -> String

Convert explicit JSON contract tokens into the expression syntax accepted by the existing property parser.

Supported explicit tokens:

• arg:N names callee argument N and becomes internal Arg_N.
• const:N names an integer constant and becomes N.
• ty:T names a type parameter/type identifier and becomes T.

Unprefixed strings are kept unchanged for compatibility with older entries such as "0", "T", and "1".