v1.9.0 — download resume, retry, notifications

🔄 Download Resume\nN_m3u8DL-RE now runs with --enable-resume — interrupted downloads pick up where they left off.\n\n## 🔁 Retry Failed Jobs\nPOST /retry/<id> endpoint lets the extension re-run failed or completed downloads.\n\n## 🔔 Completion Notifications\nBrowser notification fires when each download completes, showing the filename.\n\nIncludes all v1.8.0 features: M3U8 variant parsing, file size display, emoji icons, batch Grab All, expanded type labels.