feat(flutter): 统一二级页头并恢复新剧暖色

lib/pages/downloads/downloads_page.dart

@@ -18,6 +18,7 @@ import '../../core/theme/app_dimens.dart';
 import '../../core/theme/app_theme.dart';
 import '../../core/widgets/auth_gate.dart';
 import '../../core/widgets/empty_state.dart';
+import '../../core/widgets/plain_page_scaffold.dart';
 import '../../l10n/app_localizations.dart';
 import '../player/player_view.dart';
 import 'downloads_binding.dart';
@@ -55,20 +56,13 @@ class _DownloadsPageState extends State<DownloadsPage> {
     final signedIn = context.watch<AuthController>().isSignedIn;
     return Theme(
       data: AppTheme.light(),
-      child: Scaffold(
-        key: const Key('downloads-page'),
-        backgroundColor: AppColors.ink,
-        appBar: AppBar(
-          backgroundColor: AppColors.ink,
-          foregroundColor: Colors.white,
-          title: Text(l10n.downloads),
-        ),
-        body: SafeArea(
-          top: false,
-          child: signedIn
-              ? _DownloadsBody(downloads: context.watch<DownloadController>())
-              : const AuthGatePanel(),
-        ),
+      child: PlainPageScaffold(
+        pageKey: const Key('downloads-page'),
+        backKey: const Key('downloads-back'),
+        title: l10n.downloads,
+        child: signedIn
+            ? _DownloadsBody(downloads: context.watch<DownloadController>())
+            : const AuthGatePanel(),
       ),
     );
   }