fix(home): 调整二级筛选按钮尺寸

lib/core/theme/app_dimens.dart

@@ -111,6 +111,9 @@ abstract final class AppDimens {
   static const double homeSecondaryTagHeight = 26;
   static const double homeSecondaryTagHorizontalPadding = 10;
   static const double homeSecondaryTagRadius = 13;
+  static const double homeSecondaryFilterGap = 8;
+  static const double homeSecondaryFilterVisualSize = 26;
+  static const double homeSecondaryFilterIcon = 18;
   static const double homePrimaryCategoryGap = 24;
   static const double homeSecondaryTagGap = 14;
   static const double homeSearchTopGap = 0;

lib/pages/home/widgets/home_grid_header.dart

@@ -329,22 +329,25 @@ class HomeGridHeader extends StatelessWidget {
               ),
             ),
           ),
-          const SizedBox(width: AppDimens.spaceXs),
+          const SizedBox(width: AppDimens.homeSecondaryFilterGap),
           Tooltip(
             message: l10n.filter,
             child: SizedBox.square(
               dimension: AppDimens.tapTarget,
               child: Material(
-                color: AppColors.contentSurface,
-                borderRadius: BorderRadius.circular(AppDimens.inputRadius),
+                color: AppColors.transparent,
                 child: InkWell(
                   key: const Key('home-grid-filter'),
-                  borderRadius: BorderRadius.circular(AppDimens.inputRadius),
                   onTap: callbacks.onOpenFilter,
-                  child: const Icon(
-                    Icons.filter_list_rounded,
-                    color: AppColors.navSelected,
-                    size: AppDimens.homeHeaderIcon,
+                  child: Center(
+                    child: SizedBox.square(
+                      dimension: AppDimens.homeSecondaryFilterVisualSize,
+                      child: const Icon(
+                        Icons.filter_list_rounded,
+                        color: AppColors.textTertiary,
+                        size: AppDimens.homeSecondaryFilterIcon,
+                      ),
+                    ),
                   ),
                 ),
               ),