fix(tv): restore file imports and TV feedback fixes

[PastaHimself]

Summary

• Add TV-native import actions for Flow JSON backups, master ZIP backups, and XML/OPML subscription exports.
• Add secure YouTube OPML parsing with duplicate suppression and avatar enrichment.
• Fix TV UI mode selection resetting the settings navigation.
• Make the video-player channel name actionable so users can open the channel and subscribe.
• Add regression coverage for the TV fixes and import parsing.

The reported device-sync issues were already fixed on main and remain intact:

• recommendation data uses the compatible G-counter format;
• followed channels sync independently from subscription groups.

Validation

• Added unit and regression tests.
• The repository workflow is configured for pull requests; CI should validate formatting, tests, lint, and builds.