Use fullScreenCover for Settings and Accounts on tvOS

- Replace sheet presentation with fullScreenCover for Settings and Accounts views on tvOS
- Add proper background color to Settings and Accounts screens on tvOS
- Clean up trailing whitespace in HomeView

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Shared/Settings/SettingsView.swift

@@ -134,6 +134,9 @@ struct SettingsView: View {
                 settingsList
                     .navigationTitle("Settings")
             }
+            #if os(tvOS)
+            .background(Color.background(scheme: colorScheme).ignoresSafeArea())
+            #endif
         #endif
     }