One frame of a scene as a PNG (queued).

Renders one frame of a scene at t seconds as a PNG at the scene's size: the way to look at a moment (just after a transition, mid-reveal, the last frame) before rendering the whole video. Costs 1 unit, plus a shot's price when the scene has shots (3 plus 1 for each 1.6 megapixels). It runs as a queued job: the answer is 202 with a job id at once, and GET /api/agents/jobs/<job> (or the MCP tool job) says when it is done and signs its files. A queued call is refused on the free plan with 402: its units buy only calls that answer at once, and queued jobs need a paid plan (a pass or the card plan). Returns still.png.