Ask what a form request leaves open, before generating from it

Returns up to three questions whose answers would change the form, and **usually returns none**, which is the intended answer rather than a failure. Worth calling when a person is going to see the result: a request that asks to take a payment but names no UPI id, or to branch by plan without naming the plans, produces a form with a hole in it that only they can fill. Feed the answers back as `clarifications` on `POST /v1/ai/generate-form`. Skipping this endpoint entirely is fine; generation does not require it. Runs on the cheapest tier and is not charged as a generation, being a question about a form rather than a form, though its tokens are still counted.

curl -X POST "https://example.com/v1/ai/clarify-form" \  -H "Content-Type: application/json" \  -d '{    "prompt": "string"  }'

{  "questions": [    {      "question": "string",      "why": "string",      "kind": "choice",      "options": [        "string"      ]    }  ]}