seedance-product-video: clean e-commerce product showcase videos

Turns a product photo — or, for a fictional or prototype product, a text description — into a plain-background catalog/listing clip: a precise product description plus a simple camera move, written as timestamped waypoints, become a Seedance 2.5 prompt, which this skill submits, polls, downloads, and reports the cost for.

This skill is a thin, scenario-specific layer over ofox-video-core. It owns the product-video prompt craft, the creative brief, recommended defaults, and the pre-generation cost estimate; ofox-video-core owns talking to the Ofox API correctly and safely (the OFOX_API_KEY handling, the no-resubmit rule, error-code mapping, download/verification, and reporting the downloaded file's absolute VIDEO_PATH). Read that skill's safety contract before using this one — it is not restated here.