style: 调整追剧加号颜色

lib/core/theme/app_dimens.dart

@@ -152,6 +152,7 @@ abstract final class AppDimens {
   static const double followingTabGap = 24;
   static const double followingEditIconSize = 24;
   static const double followingAddIconSize = 28;
+  static const double followingAddIconStroke = 1.5;
   static const double followingGridGap = 6;
   static const double followingGridRowGap = 12;
   static const double followingCardTextExtent = 66;

lib/pages/following/following_grid_card.dart

@@ -163,11 +163,10 @@ class FollowingAddCard extends StatelessWidget {
                 borderRadius: BorderRadius.circular(AppDimens.homeCardRadius),
               ),
               child: const Center(
-                child: Icon(
-                  Icons.add,
+                child: CustomPaint(
                   key: Key('following-add-icon'),
-                  size: AppDimens.followingAddIconSize,
-                  color: AppColors.textPrimary,
+                  size: Size.square(AppDimens.followingAddIconSize),
+                  painter: _FollowingPlusPainter(),
                 ),
               ),
             ),
@@ -177,3 +176,22 @@ class FollowingAddCard extends StatelessWidget {
     );
   }
 }
+
+class _FollowingPlusPainter extends CustomPainter {
+  const _FollowingPlusPainter();
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()
+      ..color = AppColors.textSecondary
+      ..strokeWidth = AppDimens.followingAddIconStroke
+      ..strokeCap = StrokeCap.round;
+    final center = size.center(Offset.zero);
+    canvas
+      ..drawLine(Offset(center.dx, 0), Offset(center.dx, size.height), paint)
+      ..drawLine(Offset(0, center.dy), Offset(size.width, center.dy), paint);
+  }
+
+  @override
+  bool shouldRepaint(covariant _FollowingPlusPainter oldDelegate) => false;
+}