Several minor bug fixes (#1866)

## Description
Another PR to gather small bug fixes:
- Fix aspect ratio for episodes on person page
- Use the song's artist instead of the album's artist on album page
- Fix how the dim percentage is applied to the OS screensaver dim
percentage (#1834)

### Related issues
Fixes #1851 
Fixes #1863

### Testing
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## Screenshots
<!-- Please include screenshots if the PR alters any UI elements -->

## AI or LLM usage
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and how you tested it -->

app/src/main/java/com/github/damontecres/wholphin/MainContent.kt

@@ -154,7 +154,9 @@ fun MainContent(
                 val alpha =
                     userPreferences.appPreferences.interfacePreferences.screensaverPreference.dimPercent / 100f
                 Box(
-                    Modifier.background(Color.Black.copy(alpha = alpha)),
+                    Modifier
+                        .fillMaxSize()
+                        .background(Color.Black.copy(alpha = alpha)),
                 )
             }
         }