ui(chat): MarkdownContent 支持表格渲染

AI 聊天回复中常出现 Markdown 表格语法 (| h1 | h2 | + |---|---| )，
但 MarkdownContent 仅支持 headers/lists/code，未渲染表格，
显示为原始 | 分隔文本。

修复：
1. ChatPage.tsx MarkdownContent 新增表格解析步骤（步骤 2.7）
   - 匹配 | header |
|---|---| 的多行表格块
   - 解析对齐方式 (:---, :---:, ---:)
   - 生成 <table><thead><tbody> HTML
2. 步骤 10 恢复占位符，步骤 11 解包 <table> 不被 <p> 包裹
3. ChatPage.css 新增 .md-table 样式
   - 蓝色渐变表头 + 斑马纹 + hover 高亮
   - 用户消息气泡内深色适配

frontend/src/pages/front/ChatPage.css

@@ -446,6 +446,67 @@
   line-height: 1.6;
 }
 
+.md-table {
+  width: 100%;
+  border-collapse: collapse;
+  margin: 12px 0;
+  font-size: var(--text-sm);
+  background: #fff;
+  border-radius: var(--radius-md);
+  overflow: hidden;
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
+}
+
+.md-table thead {
+  background: linear-gradient(135deg, #5B5FED 0%, #7B7FEE 100%);
+  color: #fff;
+}
+
+.md-table th {
+  padding: 10px 14px;
+  font-weight: 600;
+  text-align: left;
+  font-size: var(--text-xs);
+  letter-spacing: 0.3px;
+}
+
+.md-table td {
+  padding: 10px 14px;
+  border-bottom: 1px solid #EEF0F4;
+  color: var(--color-text-primary);
+  vertical-align: top;
+}
+
+.md-table tbody tr:last-child td {
+  border-bottom: none;
+}
+
+.md-table tbody tr:hover {
+  background: #F8F9FC;
+}
+
+.md-table tbody tr:nth-child(even) {
+  background: #FAFBFD;
+}
+
+.md-table tbody tr:nth-child(even):hover {
+  background: #F0F2F7;
+}
+
+.message-bubble.user .md-table {
+  background: rgba(255, 255, 255, 0.08);
+  color: inherit;
+}
+.message-bubble.user .md-table th,
+.message-bubble.user .md-table td {
+  color: inherit;
+  border-color: rgba(255, 255, 255, 0.15);
+}
+.message-bubble.user .md-table tbody tr:hover,
+.message-bubble.user .md-table tbody tr:nth-child(even) {
+  background: rgba(255, 255, 255, 0.05);
+}
+
 .md-hr {
   border: none;
   border-top: 1px solid var(--color-border);

frontend/src/pages/front/ChatPage.tsx

@@ -173,6 +173,42 @@ const MarkdownContent: React.FC<{ content: string }> = ({ content }) => {
       return '\x00MEDIA' + (mediaBlocks.length - 1) + '\x00';
     });
 
+    // 2.7 Extract Markdown tables: | h1 | h2 |\n|---|---| ... |
+    // 把整段表格替换为占位符，表格内容(已转义)放入 tableBlocks 数组
+    const tableBlocks: string[] = [];
+    text = text.replace(
+      /((?:^\|.+\|\r?\n)+^\|[\s\-:|]+\|\r?\n(?:^\|.+\|\r?\n?)+)/gm,
+      (_m: string, block: string) => {
+        const lines = block.trim().split(/\r?\n/).filter((l: string) => l.trim());
+        if (lines.length < 2) return block;
+        const headerCells = lines[0].split('|').slice(1, -1).map((c: string) => c.trim());
+        const alignCells = lines[1].split('|').slice(1, -1).map((c: string) => {
+          const t = c.trim();
+          const left = t.startsWith(':');
+          const right = t.endsWith(':');
+          if (left && right) return 'center';
+          if (right) return 'right';
+          if (left) return 'left';
+          return 'left';
+        });
+        const bodyRows = lines.slice(2).map((row: string) =>
+          row.split('|').slice(1, -1).map((c: string) => c.trim())
+        );
+        const thead = headerCells.map((c: string, i: number) =>
+          `<th style="text-align:${alignCells[i] || 'left'}">${c}</th>`
+        ).join('');
+        const tbody = bodyRows.map((r: string[]) =>
+          '<tr>' + r.map((c: string, i: number) =>
+            `<td style="text-align:${alignCells[i] || 'left'}">${c}</td>`
+          ).join('') + '</tr>'
+        ).join('');
+        const html = `<table class="md-table"><thead><tr>${thead}</tr></thead><tbody>${tbody}</tbody></table>`;
+        const idx = tableBlocks.length;
+        tableBlocks.push(html);
+        return '\x00TABLE' + idx + '\x00';
+      }
+    );
+
     // 3. Headers
     text = text.replace(/^#### (.+)$/gm, '<h4 class="md-h4">$1</h4>');
     text = text.replace(/^### (.+)$/gm, '<h4 class="md-h4">$1</h4>');
@@ -206,6 +242,7 @@ const MarkdownContent: React.FC<{ content: string }> = ({ content }) => {
     // 10. Restore code blocks and inline codes
     text = text.replace(/\x00CODEBLOCK(\d+)\x00/g, (_m: string, idx: string) => codeBlocks[parseInt(idx)] || '');
     text = text.replace(/\x00INLINE(\d+)\x00/g, (_m: string, idx: string) => inlineCodes[parseInt(idx)] || '');
+    text = text.replace(/\x00TABLE(\d+)\x00/g, (_m: string, idx: string) => tableBlocks[parseInt(idx)] || '');
 
     // 11. Wrap in paragraph and clean up
     text = '<p class="md-p">' + text + '</p>';
@@ -215,6 +252,7 @@ const MarkdownContent: React.FC<{ content: string }> = ({ content }) => {
     text = text.replace(/<p class="md-p">(<ul[\s\S]*?<\/ul>)<\/p>/g, '$1');
     text = text.replace(/<p class="md-p">(<hr[\s\S]*?)<\/p>/g, '$1');
     text = text.replace(/<p class="md-p">(<blockquote[\s\S]*?<\/blockquote>)<\/p>/g, '$1');
+    text = text.replace(/<p class="md-p">(<table[\s\S]*?<\/table>)<\/p>/g, '$1');
 
     // 12. 拆分为文本片段与媒体组件
     const parts = text.split(/(\x00MEDIA\d+\x00)/g);