fix(flutter): 评论入口增加登录闸

test/player/player_fullscreen_test.dart

@@ -69,6 +69,34 @@ void main() {
     );
   });
 
+  testWidgets('should_gate_comments_before_opening_sheet_when_signed_out', (
+    tester,
+  ) async {
+    await _pumpApp(tester);
+    await _openSeriesPlayer(tester);
+
+    await tester.tap(find.byKey(const Key('player-rail-comments')));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Sign in to continue'), findsOneWidget);
+    expect(find.byKey(const Key('player-comments-sheet')), findsNothing);
+  });
+
+  testWidgets('should_open_feed_comments_when_signed_in', (tester) async {
+    SharedPreferencesAsyncPlatform.instance =
+        InMemorySharedPreferencesAsync.withData({
+          'auth.accessToken': 'access',
+          'auth.refreshToken': 'refresh',
+          'auth.user': '{"uid":"9","nickname":"Viewer","avatarUrl":""}',
+        });
+    await _pumpApp(tester);
+
+    await tester.tap(find.byKey(const Key('rail-comments')));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('player-comments-sheet')), findsOneWidget);
+  });
+
   testWidgets('should_show_center_toggle_only_when_paused', (tester) async {
     await _pumpApp(tester);
     await _openSeriesPlayer(tester);