fix: 修复 msg_text_color 类型在购买分发、校验和后台管理中的遗漏

- ShopService: 购买分发 match 新增 msg_text_color → DecorationService
- ShopController: 购买公告 match 新增 msg_text_color
- Admin/ShopItemController: 后台 validation type 校验新增 msg_text_color
- admin/shop/index.blade: 类型标签映射和下拉选项新增文字颜色

resources/views/admin/shop/index.blade.php

@@ -24,6 +24,7 @@
             'sign_repair' => ['label' => '签到补签卡', 'color' => 'bg-teal-100 text-teal-700'],
             'msg_bubble' => ['label' => '消息气泡', 'color' => 'bg-violet-100 text-violet-700'],
             'msg_name_color' => ['label' => '昵称颜色', 'color' => 'bg-pink-100 text-pink-700'],
+            'msg_text_color' => ['label' => '文字颜色', 'color' => 'bg-cyan-100 text-cyan-700'],
             'avatar_frame' => ['label' => '头像框', 'color' => 'bg-amber-100 text-amber-700'],
         ];
         $isSuperAdmin = Auth::id() === 1;
@@ -292,6 +293,7 @@
                                 <option value="sign_repair">sign_repair — 签到补签卡</option>
                                 <option value="msg_bubble">msg_bubble — 消息气泡</option>
                                 <option value="msg_name_color">msg_name_color — 昵称颜色</option>
+                                <option value="msg_text_color">msg_text_color — 文字颜色</option>
                                 <option value="avatar_frame">avatar_frame — 头像框</option>
                             </select>
                         </div>