prd-questions

Use when the user wants every open question in a PRD resolved interactively — "ask me all questions", "/prd-questions", "let's resolve the open questions". Sweeps the PRD for open questions and ambiguities, asks them in batched multiple-choice form with recommendations, folds every answer back into the owning spec section, and empties the Open Questions section. Stage 2 of the new-app-pipeline.