feat: Excel 导入预检与动态问答，AI 聊天/文件解析体验修复

- imports: 新增 preflight_import 预检报告（判定/分阶段统计/阻断归因/问题/下一步/错误示例），导入任务 settings 落库（映射/校区/更新/重复/未匹配策略），预览应用策略，向导提交写操作日志
- ai-chat: 新增 excel_analyze（ExcelJS）工具，移除附件/上下文截断，start_import_wizard 支持确认参数，ui.import_preflight SSE，预览确认写操作日志
- admin: ImportPreflightCard 渲染与持久化，聊天抽屉布局/侧边栏修复，考勤页 CSS 引入，费用/学生页接口 schema 校验修复

apps/admin/src/components/AiChat/ImportPreflightCard.tsx

@@ -0,0 +1,115 @@
+import React from 'react';
+import { TableOutlined } from '@ant-design/icons';
+import { Card, Flex, Space, Tag, Typography } from 'antd';
+import type {
+  AiImportPreflight,
+  AiImportPreflightVerdict,
+} from './types';
+
+const VERDICT_META: Record<
+  AiImportPreflightVerdict,
+  { label: string; color: string }
+> = {
+  ready: { label: '可导入', color: 'success' },
+  needs_input: { label: '需要确认', color: 'warning' },
+  blocked: { label: '暂无法导入', color: 'error' },
+};
+
+/**
+ * 上传 Excel 后的“可插入性预检报告”卡片：展示判定结论、
+ * 分阶段统计、阻断原因、待确认问题与下一步建议。
+ */
+export const ImportPreflightCard: React.FC<{ preflight: AiImportPreflight }> = ({
+  preflight,
+}) => {
+  const verdict = VERDICT_META[preflight.verdict] ?? VERDICT_META.needs_input;
+  return (
+    <Card
+      size="small"
+      className="ai-chat-preflight-card"
+      title={
+        <Flex gap={8} align="center" wrap>
+          <TableOutlined />
+          <Typography.Text strong>Excel 导入预检</Typography.Text>
+          <Tag color={verdict.color}>{verdict.label}</Tag>
+        </Flex>
+      }
+    >
+      <Space orientation="vertical" size={12} style={{ width: '100%' }}>
+        {preflight.stages.length > 0 ? (
+          <Space orientation="vertical" size={10} style={{ width: '100%' }}>
+            {preflight.stages.map((stage) => (
+              <Flex key={stage.stepKey} vertical gap={4}>
+                <Flex gap={8} align="center" wrap>
+                  <Typography.Text strong>{stage.label}</Typography.Text>
+                  <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+                    {stage.sheetNames.join('、')}
+                  </Typography.Text>
+                </Flex>
+                <Space size={4} wrap>
+                  <Tag color="blue">共 {stage.total} 行</Tag>
+                  <Tag color="green">新建 {stage.create}</Tag>
+                  <Tag color="orange">更新 {stage.update}</Tag>
+                  <Tag color="red">错误 {stage.error}</Tag>
+                  <Tag>跳过 {stage.skip}</Tag>
+                </Space>
+              </Flex>
+            ))}
+          </Space>
+        ) : (
+          <Typography.Text type="secondary">未识别到可导入的工作表</Typography.Text>
+        )}
+
+        {preflight.blocks.length > 0 && (
+          <Space orientation="vertical" size={4} style={{ width: '100%' }}>
+            <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+              阻断原因
+            </Typography.Text>
+            {preflight.blocks.map((block) => (
+              <Flex key={block.code} gap={8} align="baseline" wrap>
+                <Tag color="red">{block.label}</Tag>
+                <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+                  {block.message}（{block.count} 行）
+                </Typography.Text>
+              </Flex>
+            ))}
+          </Space>
+        )}
+
+        {preflight.questions.length > 0 && (
+          <Space orientation="vertical" size={4} style={{ width: '100%' }}>
+            <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+              需要确认
+            </Typography.Text>
+            {preflight.questions.map((question) => (
+              <Flex key={question.key} gap={8} align="baseline" wrap>
+                <Tag color="gold">{question.label}</Tag>
+                {question.description && (
+                  <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+                    {question.description}
+                  </Typography.Text>
+                )}
+              </Flex>
+            ))}
+          </Space>
+        )}
+
+        {preflight.nextSteps.length > 0 && (
+          <Space orientation="vertical" size={4} style={{ width: '100%' }}>
+            <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+              下一步建议
+            </Typography.Text>
+            {preflight.nextSteps.map((step) => (
+              <Flex key={step.key} gap={8} align="baseline" wrap>
+                <Tag color="blue">{step.label}</Tag>
+                <Typography.Text type="secondary" style={{ fontSize: 12 }}>
+                  {step.description}
+                </Typography.Text>
+              </Flex>
+            ))}
+          </Space>
+        )}
+      </Space>
+    </Card>
+  );
+};