attach_product_to_portfolio
Place an existing product under a portfolio (adds it to the portfolio's `products[]` in `.upg/portfolio.upg`). Resolves the portfolio against the portfolio document and auto-registers the product on the portfolio registry. Use after `create_product`, or pass `portfolio_id` to `create_product` directly.
Workspace & Portfoliosatomic (single portfolio.upg flush).
Arguments
product_idstringrequiredProduct id (from create_product / list_local_products)
portfolio_idstringrequiredPortfolio id (from list_portfolios)
Returns
Shape
{ product_id, container_id, container_kind: "portfolio", container_title?, already_member, registered }