fix: resolve current episode highlight color and focus clash

[mattsigal]

Pull Request

Summary

Implements a visual theme-appropriate distinction for the "next up" episode card highlights.

Related Issues

Link related issues or tickets separated by commas.

• Closes #
• Fixes #
• Related to #

Type of Change

• Bug fix
• New feature
• Refactor
• Performance improvement
• UI/UX update
• Documentation update
• Build/CI change
• Other (describe):

Changes Made

• Modified _EpisodeListCardState.build in lib/ui/screens/detail/item_detail_screen.dart to check showFocusBorder first. Active focus highlights now cleanly override next-up borders.
• Styled the next-up episode (widget.isCurrent when not focused) using AppColorScheme.onSurface (cyan in Neon Pulse, white in the default Moonfin theme)
• Fixed outdated preference migration key assertions (pref_audio_preference_split_v1 -> v2) in audio_migration_test.dart to keep the test suite passing.

Platform

• Android
• iOS
• macOS
• Windows
• Linux
• All / Shared code

Testing

Describe how this change was tested.

• Tested on emulator / simulator
• Tested on physical device
• Manual testing completed
• Not tested (explain why):

Test Steps

1. Navigate to a TV Series detail page in the Neon Pulse theme.
2. Verify that the next-up episode card has a thicker, cyan outline when not focused.
3. Move focus to the card and verify it scales and displays the primary pink focus border.

Screenshots (if applicable)

Original:

New (with both themes):

Checklist

• Code builds successfully
• Code follows project style and conventions
• No unnecessary commented-out code
• No new warnings introduced

[RadicalMuffinMan]

rebase on main