Function json_to_value 

pub fn json_to_value(
    engine: &mut Engine<'_>,
    context: Tracked<'_, Context<'_>>,
    library: &Library,
    json: &Value,
) -> Result<Value, ConvertError>

Convert JSON to Typst Value.

• Objects with “func” field → Content
• Objects without “func” → Dict
• Arrays → Array
• Primitives → corresponding Value variant