At most one question, and only when it is needed

lib/meal-question.ts decides it.

• Oil is asked about only when the estimator put it on the plate as something it could not see, or asked about it itself.
• Never when the plate has no fat row (a cup of tea), and never when the amount is already known (typed, labelled, measured).
• The answer goes onto the row already there, so a plate never ends up with two.
• It is answered on the device, so the card can print what each answer adds.
• Anything else is the estimator's own first question and goes back to /clarify.

The wire still allows two questions and the prompt still asks for up to two; the app puts the first. Tightening the prompt is a server change and needs pnpm eval.

See the-ask and accuracy-is-measured.