feat: 新增5种表格主题风格

- ocean 海洋蓝：清爽专业，适合商务科技场景
- forest 森林绿：自然护眼，适合长时间阅读
- sunset 日落橙：温暖活力，吸引注意力
- lavender 薰衣草紫：优雅浪漫，柔和梦幻
- minimal 极简灰：干净现代，强调内容本身

现在共10种表格主题可选

server.js

@@ -470,6 +470,51 @@ const tableThemes = {
         borderColor: '#d4a5a5',
         stripeColor: '#f6e8c3',
         titleColor: '#444444'
+    },
+    ocean: {
+        bgColor: '#f0f8ff',
+        headerBg: '#0077b6',
+        headerColor: '#ffffff',
+        cellColor: '#023e58',
+        borderColor: '#90e0ef',
+        stripeColor: '#caf0f8',
+        titleColor: '#023e58'
+    },
+    forest: {
+        bgColor: '#f5faf5',
+        headerBg: '#2d6a4f',
+        headerColor: '#ffffff',
+        cellColor: '#1b4332',
+        borderColor: '#95d5b2',
+        stripeColor: '#d8f3dc',
+        titleColor: '#1b4332'
+    },
+    sunset: {
+        bgColor: '#fff8f0',
+        headerBg: '#e85d04',
+        headerColor: '#ffffff',
+        cellColor: '#6a040f',
+        borderColor: '#ffba08',
+        stripeColor: '#fff3e0',
+        titleColor: '#6a040f'
+    },
+    lavender: {
+        bgColor: '#faf5ff',
+        headerBg: '#7c3aed',
+        headerColor: '#ffffff',
+        cellColor: '#4c1d95',
+        borderColor: '#c4b5fd',
+        stripeColor: '#ede9fe',
+        titleColor: '#4c1d95'
+    },
+    minimal: {
+        bgColor: '#ffffff',
+        headerBg: '#f8f9fa',
+        headerColor: '#212529',
+        cellColor: '#495057',
+        borderColor: '#dee2e6',
+        stripeColor: '#f8f9fa',
+        titleColor: '#212529'
     }
 };
 
@@ -780,7 +825,7 @@ app.get('/api/docs', (req, res) => {
                 params: {
                     data: { type: 'string', required: true, description: 'CSV 格式数据（第一行表头）' },
                     title: { type: 'string', default: '', description: '表格标题' },
-                    theme: { type: 'string', default: 'default', options: ['default', 'dark', 'macarons', 'gradient', 'retro'], description: '主题风格' },
+                    theme: { type: 'string', default: 'default', options: ['default', 'dark', 'macarons', 'gradient', 'retro', 'ocean', 'forest', 'sunset', 'lavender', 'minimal'], description: '主题风格' },
                     fontSize: { type: 'number', default: 14, description: '字体大小' },
                     cellPadding: { type: 'number', default: 12, description: '单元格内边距' },
                     borderWidth: { type: 'number', default: 1, description: '边框宽度' },