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/YatteeApp.swift

@@ -184,6 +184,22 @@ struct YatteeApp: App {
                         .appEnvironment(appEnvironment)
                 }
                 #endif
+                #if os(tvOS)
+                // tvOS sheets render as a small centered card that cannot fit
+                // the sidebar-detail layout — use a full screen cover instead.
+                .fullScreenCover(isPresented: $showingLegacyAccountsImport) {
+                    NavigationStack {
+                        TVSidebarDetailContainer(
+                            systemImage: "person.badge.key",
+                            title: String(localized: "migration.accounts.title")
+                        ) {
+                            LegacyAccountsImportView()
+                        }
+                        .appEnvironment(appEnvironment)
+                    }
+                    .background(Color.black.ignoresSafeArea())
+                }
+                #else
                 .sheet(isPresented: $showingLegacyAccountsImport) {
                     NavigationStack {
                         LegacyAccountsImportView()
@@ -193,6 +209,7 @@ struct YatteeApp: App {
                     .frame(minWidth: 560, minHeight: 560)
                     #endif
                 }
+                #endif
                 #if os(iOS)
                 .sheet(isPresented: $showingSettings) {
                     SettingsView()