Media downloader for DeepSeek Harness

Key features

• Stream a media URL to disk with redirect handling and a 60s timeout.
• Only download content you have rights to.
• Pure regex quality + extension extraction, zero network access.
• Zero build step — pure ESM, the published package is the runtime code.
• The pure core (isMedia, getQuality, getExt, detectSite) is exported for testing.