Function render 

pub fn render(
    protocol_json: &str,
    state_json: &str,
    entry: &str,
    request_path: &str,
    plugin: Option<String>,
) -> Result<String, JsValue>

Render a pre-built WebUI protocol with state data.

Arguments

• protocol_json — JSON string of the serialized WebUIProtocol.
• state_json — JSON string of the state data.
• plugin — Optional plugin identifier (e.g., "fast").

Returns

The rendered HTML string, or throws a JS error on failure.