Function diagnostics_collect 

pub async fn diagnostics_collect(
    config: BundleConfig,
    redactor: State<'_, DiagnosticsRedactorHandle>,
    app: AppHandle,
) -> Result<BundleRef, AppError>

Collect a diagnostic bundle according to config.

Resolves the app paths from the Tauri AppHandle, builds the bundle via collect_bundle, and returns a BundleRef that the frontend holds between the “Generate” and “Save” steps.