Playback diagnostics panel

[diprapaul700078-ui]

Describe your suggested feature

Add a dedicated diagnostics screen for playback that shows stream URL, headers, extractor choice, decoder path, subtitle track, DRM state, and the last failure reason. This would make playback bugs much easier to report and fix.

Other details

No response

Acknowledgements

• My suggestion is NOT about adding a new provider
• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.