Function extract_json 

pub fn extract_json(raw: &str) -> Result<NormalizedOutput, NormalizationError>

Extract a JSON body from a raw LLM response.

Tries extraction strategies in order of specificity:

1. Fenced JSON (\``json`)
2. Generic fence (\```) whose content parses as JSON
3. Direct JSON (trimmed input starts with { or [)
4. Embedded JSON (first { to last balanced })

Returns the extracted body and the method used, or an error if no JSON could be found.