Fix tvOS legacy import rows acting as a single Remove button

On tvOS a Form row is one focusable unit, so the legacy account/source
cards - header, credential fields, and both buttons stacked in a single
row - focused as a whole and every click fired the first button (Remove),
making credentials and Import unreachable.

- Split the tvOS rows into individually focusable rows (info header,
  fields, Import, Remove), keeping the card layout on iOS/macOS
- Wrap the tvOS entry points in TVSidebarDetailContainer and drop the
  tvOS navigationTitle that rendered as a ghost behind the form
- Present the review screen from the first-launch alert as a
  fullScreenCover on tvOS: sheets render as a small transparent card
  that cannot fit the sidebar layout (Menu button dismisses the cover)
- Dim disabled TVSettingsButtonStyle buttons
- Widen the row icon frame for tvOS glyph sizes and skip the caption
  when it would repeat the host shown as the title

Yattee/Views/Settings/TVSettingsButtonStyles.swift

@@ -88,9 +88,11 @@ struct TVSettingsTextField: View {
 /// Button style for settings forms - subtle focus effect without glow
 struct TVSettingsButtonStyle: ButtonStyle {
     @Environment(\.isFocused) private var isFocused
+    @Environment(\.isEnabled) private var isEnabled
 
     func makeBody(configuration: Configuration) -> some View {
         configuration.label
+            .opacity(isEnabled ? 1 : 0.4)
             .padding(.horizontal, 20)
             .padding(.vertical, 12)
             .background(