release: document bundled binary license obligations

[ubugeeei]

Finding

The project is MIT licensed, but release artifacts may bundle ffmpeg/ffprobe/Chromium-related binaries with their own redistribution obligations.

Evidence

• package.json depends on @ffmpeg-installer/ffmpeg, @ffprobe-installer/ffprobe, Electron, and Puppeteer.
• No NOTICE or third-party binary license notes are present.

Acceptance criteria

• Document third-party binary licenses and redistribution expectations.
• Add a release checklist item for license notices.
• Ensure packaged artifacts include required notices.

[ubugeeei]

対応済みです。修正は PR #1 / commit 9cf4498 に反映済みです。