Function build_protocol 

pub fn build_protocol(
    files: JsValue,
    entry: &str,
    projection_manifests: Option<JsValue>,
    dom: Option<String>,
) -> Result<Vec<u8>, JsValue>

Build protocol protobuf bytes from virtual files without rendering.

dom accepts "shadow" (default) or "light" for unwrapped components; authored open Shadow roots remain Shadow in either mode.

Returns the serialized WebUIProtocol as protobuf bytes.