fix: 后台管理子类别筛选按钮显示选中状态

- 添加"全部"按钮，点击可清除筛选
- 选中状态：蓝色背景白色文字
- 未选中状态：白色背景灰色文字+边框
- 用户点击后能看到明显的视觉变化
- 根据当前筛选值动态更新按钮样式

templates/admin.html

@@ -534,9 +534,21 @@
                 container.innerHTML = '';
                 return;
             }
-            container.innerHTML = cat.subcategories.map(sub => `
-                <button onclick="${filterFunction}('${sub.id}')" class="px-3 py-1 rounded text-sm bg-white border text-gray-600 hover:bg-gray-100">
-                    <i class="${sub.icon} mr-1"></i>${sub.name}
+            
+            // 获取当前筛选值
+            let currentFilter = '';
+            if (categoryId === 'ai-models') currentFilter = modelSubcategoryFilter;
+            else if (categoryId === 'gpus') currentFilter = gpuSubcategoryFilter;
+            else if (categoryId === 'cpus') currentFilter = cpuSubcategoryFilter;
+            else if (categoryId === dynamicCategoryId) currentFilter = dynamicSubcategoryFilter;
+            
+            container.innerHTML = `
+                <button onclick="${filterFunction}('')" class="px-3 py-1 rounded text-sm ${currentFilter === '' ? 'bg-indigo-600 text-white' : 'bg-white border text-gray-600 hover:bg-gray-100'}">
+                    <i class="ri-apps-line mr-1"></i>全部
+                </button>
+            ` + cat.subcategories.map(sub => `
+                <button onclick="${filterFunction}('${sub.id}')" class="px-3 py-1 rounded text-sm ${currentFilter === sub.id ? 'bg-indigo-600 text-white' : 'bg-white border text-gray-600 hover:bg-gray-100'}">
+                    <i class="${sub.icon || 'ri-folder-line'} mr-1"></i>${sub.name}
                 </button>
             `).join('');
         }