Function normalize 

pub fn normalize(icl: &str) -> Result<String>

Normalize ICL text to canonical form

Pipeline: parse → normalize AST → serialize → compute hash

Guarantees

• Idempotent: normalize(normalize(x)) == normalize(x)
• Deterministic: same input always produces same output
• Semantic preserving: parse(normalize(x)) preserves all meaning

Errors

Returns ParseError for invalid input or NormalizationError if the contract cannot be canonicalized.