SABnzbd client (queue, history, pause/resume, delete, retry) with lenient
number decoding and API-key-safe errors. Downloads view polls while
visible, shows queue and history, and supports pause, delete (with
confirmation) and retry. Add dev/ with pinned Radarr/Sonarr/SABnzbd
containers wired together for manual testing.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
