feat: 字段列表优化 - 输入限制、选中样式、取消选中

- FieldEditor: 字段名称maxLength=20，描述maxLength=50
- FieldItem: 统一有无描述时的垂直居中布局，选中左侧竖线+背景高亮
- FieldList: 点击已选中字段可取消选中，选中态加shadow和ring效果
- index: 支持selectedIndex=-1取消选中

src/pages/TestDataGenerator/components/FieldEditor.tsx

@@ -80,6 +80,7 @@ export default function FieldEditor({ field, onChange }: FieldEditorProps) {
             value={field.name}
             onChange={(e) => handleNameChange(e.target.value)}
             placeholder={t('testDataGenerator_fieldNamePlaceholder')}
+            maxLength={20}
             className="h-9"
           />
         </div>
@@ -92,6 +93,7 @@ export default function FieldEditor({ field, onChange }: FieldEditorProps) {
             value={field.description || ''}
             onChange={(e) => handleDescriptionChange(e.target.value)}
             placeholder={t('testDataGenerator_fieldDescriptionPlaceholder')}
+            maxLength={50}
             className="h-9"
           />
         </div>

src/pages/TestDataGenerator/components/FieldItem.tsx

@@ -1,6 +1,6 @@
 /**
  * 字段项组件
- * 展示单个字段的基本信息
+ * 展示单个字段的基本信息，适配固定高度卡片
  */
 
 import { useI18n } from '@/utils/chromeI18n';
@@ -20,30 +20,45 @@ export default function FieldItem({ field, onClick, isSelected }: FieldItemProps
 
   return (
     <div
-      className={`flex-1 cursor-pointer p-2 rounded-md transition-colors ${
-        isSelected ? 'bg-primary/10' : 'hover:bg-muted/50'
+      className={`flex-1 min-w-0 cursor-pointer rounded-md transition-all ${
+        isSelected
+          ? 'bg-primary/10 pl-2 border-l-2 border-l-primary'
+          : 'hover:bg-muted/50 border-l-2 border-l-transparent'
       }`}
       onClick={onClick}
     >
-      <div className="flex items-center gap-2">
-        <span className="font-medium text-sm text-foreground truncate">{field.name}</span>
-        <Badge variant="secondary" className="text-xs">
+      <div
+        className={`h-full ${field.description ? 'flex flex-col justify-center' : 'flex items-center'}`}
+      >
+        {/* 第一行：字段名 + 标签 */}
+        <div className="flex items-center gap-1.5 overflow-hidden">
+          <span className="font-medium text-sm text-foreground truncate shrink-0 max-w-[140px]">
+            {field.name}
+          </span>
+          <Badge variant="secondary" className="text-[10px] shrink-0 px-1 py-0">
             {generator?.name || field.generatorId}
           </Badge>
           {!field.required && (
-          <Badge variant="outline" className="text-xs text-muted-foreground">
+            <Badge
+              variant="outline"
+              className="text-[10px] shrink-0 px-1 py-0 text-muted-foreground"
+            >
               {field.nullRate}%
             </Badge>
           )}
           {field.unique && (
-          <Badge variant="outline" className="text-xs text-blue-500">
+            <Badge variant="outline" className="text-[10px] shrink-0 px-1 py-0 text-blue-500">
               {t('testDataGenerator_unique')}
             </Badge>
           )}
         </div>
+        {/* 第二行：描述 */}
         {field.description && (
-        <p className="text-xs text-muted-foreground mt-1 truncate">{field.description}</p>
+          <p className="text-[11px] text-muted-foreground mt-0.5 truncate leading-tight">
+            {field.description}
+          </p>
         )}
       </div>
+    </div>
   );
 }

src/pages/TestDataGenerator/components/FieldList.tsx

@@ -74,12 +74,12 @@ function SortableFieldItem({
     <div
       ref={setNodeRef}
       style={style}
-      className={`group relative rounded-lg border transition-colors ${
+      className={`group relative rounded-lg border transition-all ${
         isDragging ? 'border-primary shadow-lg' : ''
       } ${
         isSelected
-          ? 'border-primary bg-primary/5'
-          : 'border-border hover:border-muted-foreground/30'
+          ? 'border-primary bg-primary/8 shadow-sm ring-1 ring-primary/20'
+          : 'border-border hover:border-muted-foreground/30 hover:shadow-sm'
       }`}
     >
       <div className="flex items-center gap-2 h-full px-3 py-2">
@@ -131,6 +131,14 @@ export default function FieldList({
     }),
   );
 
+  // 点击已选中的字段时取消选中
+  const handleToggleSelect = useCallback(
+    (index: number) => {
+      onSelect(selectedIndex === index ? -1 : index);
+    },
+    [selectedIndex, onSelect],
+  );
+
   const handleDragEnd = (event: DragEndEvent) => {
     const { active, over } = event;
     if (!over || active.id === over.id) return;
@@ -232,7 +240,7 @@ export default function FieldList({
                             <SortableFieldItem
                               field={field}
                               isSelected={selectedIndex === realIndex}
-                              onSelect={() => onSelect(realIndex)}
+                              onSelect={() => handleToggleSelect(realIndex)}
                               onRemove={() => onRemove(realIndex)}
                             />
                           </div>
@@ -248,7 +256,7 @@ export default function FieldList({
                         key={field.id}
                         field={field}
                         isSelected={selectedIndex === index}
-                        onSelect={() => onSelect(index)}
+                        onSelect={() => handleToggleSelect(index)}
                         onRemove={() => onRemove(index)}
                       />
                     ))}

src/pages/TestDataGenerator/index.tsx

@@ -173,8 +173,8 @@ export default function TestDataGeneratorPage() {
     generate(fields, count, format === 'csv');
   }, [fields, count, format, generate]);
 
-  // 获取选中的字段
-  const selectedField = selectedIndex !== null ? fields[selectedIndex] : null;
+  // 获取选中的字段（-1 或 null 表示未选中）
+  const selectedField = selectedIndex !== null && selectedIndex >= 0 ? fields[selectedIndex] : null;
 
   return (
     <div className="min-h-screen bg-background text-foreground antialiased selection:bg-primary/20">