style(home): 观看全集按钮改用暖深炭灰

lib/core/theme/app_colors.dart

@@ -30,8 +30,8 @@ abstract final class AppColors {
   /// 首页及剧集播放页视频信息文案：参考设计图的 65% 半透明白。
   static const homeFeedVideoCopy = Color(0xA6FFFFFF);
 
-  /// 首页观看全集按钮：参考设计稿的中性深灰表面。
-  static const watchAllSurface = Color(0xFF333333);
+  /// 首页观看全集按钮：参考设计稿的按钮灰，并叠入品牌红暖调。
+  static const watchAllSurface = Color(0xFF3B3434);
 
   /// 主操作、选中态、播放进度。旧品牌橙已全量映射为品牌红（2026-10 改版）。
   static const blue = Color(0xFFF04E4E);

test/home/feed_watch_all_gradient_test.dart

@@ -7,6 +7,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:fruitshorts/core/data/models/drama.dart';
+import 'package:fruitshorts/core/theme/app_colors.dart';
 import 'package:fruitshorts/l10n/app_localizations.dart';
 import 'package:fruitshorts/pages/player/widgets/home_feed_recommend_panel.dart';
 
@@ -15,7 +16,6 @@ const _width = 280.0;
 const _sampleInset = 16;
 const _sampleY = 4;
 const _rgbaChannels = 4;
-const _surfaceChannel = 0.2;
 const _surfaceTolerance = 0.01;
 const _drama = Drama(
   id: 'surface',
@@ -71,9 +71,18 @@ void main() {
       image.dispose();
       for (final sample in [left, middle, right]) {
         expect(sample.a, 1);
-        expect(sample.r, closeTo(_surfaceChannel, _surfaceTolerance));
-        expect(sample.g, closeTo(_surfaceChannel, _surfaceTolerance));
-        expect(sample.b, closeTo(_surfaceChannel, _surfaceTolerance));
+        expect(
+          sample.r,
+          closeTo(AppColors.watchAllSurface.r, _surfaceTolerance),
+        );
+        expect(
+          sample.g,
+          closeTo(AppColors.watchAllSurface.g, _surfaceTolerance),
+        );
+        expect(
+          sample.b,
+          closeTo(AppColors.watchAllSurface.b, _surfaceTolerance),
+        );
       }
     });
   });