A worker hitting a wall only a human can clear (captcha, email/SMS OTP, 2FA,
a decision) calls ask_operator with a precise question and an optional
screenshot. The question lands in the intent's transcript as a user-role turn
with an attachment card (the same {text, attachments} shape chat uploads use,
so the existing transcript UI renders it natively), and the intent pauses. The
operator replies through the existing message-to-worker flow; the reply resumes
the run with the answer as the next input. Images are whitelisted (png/jpg/
jpeg/webp/gif), capped at 10MB, and copied into the task uploads dir.
Closes#41
