- Handle string entries in createPanel (e.g. 'https://...mp4')
instead of dropping them as null — restores legacy string URL support.
- Add console.log for HLS detection so integration tests can verify
HLS playback paths are exercised.
Without this, Chrome blocks chrome.runtime.getURL('interceptors.js')
in Manifest V3, causing HLS detection to silently fail.
Added regression test to prevent future removal.