Update emby to version 4.9.1

[al-lac]

🤖 This is an automated pull request to update emby to version 4.9.1. This PR must be reviewed and tested before merging.

Auto-generated update considerations:

• Database performance improvements may require reindexing or optimization
• Upgrade to .NET 8 could impact compatibility with older systems
• New maintenance mode feature may affect accessibility during upgrades
• Changes to environment variables for remote quality settings (split into two)
• New WebStreams plugin might require additional configuration
• New library options for merging top-level folders, multi-part detection, and multi-version detection
• Added experimental HEVC transcoding option
• New option to limit resolution of all transcoding
• Changes to user and app settings organization
• New library filter for duplicates
• Added support for external audio tracks for movies and episodes
• New library options for chapter generation
• Changes to collection grouping options
• Database integrity checks now run before backups
• Improvements to hardware detection timing on startup
• Support for reordering transcoding codec settings
• Changes to realtime monitor delay, which may affect scanning behavior
• Collections library has been restored
• New series recording option to check all libraries for existing episodes

Original GitHub release notes

[al-lac]

🤖 This is an automated summary of installation tests for emby:

• ✅ App successfully installed in umbrel-dev instance
• ✅ App successfully listed in umbrel.yaml
• ✅ App UI successfully returns a 200 status code
• 📸 Screenshot of the app:
  

This PR must still be reviewed and tested before merging.

[github-actions]

🎉   Linting finished with no errors or warnings   🎉

Thank you for your submission! This is an automated linter that checks for common issues in pull requests to the Umbrel App Store.

[al-lac]

Tested update on Umbrel dev instance.