Function json_to_simple_value 

pub fn json_to_simple_value(json: &Value) -> Result<Value, ConvertError>

Convert JSON value to Typst Value (simple, without Content reconstruction).

This is a lightweight conversion that maps JSON types directly to Typst types. Objects with {"func": ...} are converted to Dict, not Content.

For Content reconstruction, use Inputs::from_json_with_content().