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/server/src/imports/imports.controller.spec.ts

@@ -0,0 +1,74 @@
+import { ImportsController } from './imports.controller';
+
+describe('ImportsController', () => {
+  const principalRequest = {
+    user: { id: 7, username: 'admin', permissions: [], isSuperAdmin: true },
+    headers: { 'user-agent': 'jest-agent' },
+    connection: { remoteAddress: '127.0.0.1' },
+  };
+
+  it('提交导入阶段成功后写入操作日志', async () => {
+    const commitStep = jest.fn().mockResolvedValue({
+      runId: 'run-1',
+      stepKey: 'students',
+      status: 'committed',
+      created: 2,
+      updated: 0,
+      skipped: 0,
+      failed: 0,
+      total: 2,
+      nextStepKey: null,
+      runStatus: 'committed',
+      message: '阶段「学生档案」提交完成：新建 2、更新 0、跳过 0、失败 0；全部阶段已完成',
+    });
+    const opLog = { log: jest.fn().mockResolvedValue(undefined) };
+    const controller = new ImportsController({ commitStep } as never, opLog as never);
+
+    await controller.commit(
+      principalRequest as never,
+      'run-1',
+      'students',
+      { decisions: [] },
+    );
+
+    expect(opLog.log).toHaveBeenCalledWith(
+      expect.objectContaining({
+        userId: 7,
+        username: 'admin',
+        module: '批量导入',
+        action: '提交导入阶段',
+        detail: expect.stringContaining('提交完成'),
+        targetType: 'import_run',
+        ipAddress: '127.0.0.1',
+        userAgent: 'jest-agent',
+      }),
+    );
+  });
+
+  it('非 committed 回执（conflict/already_committed）不重复写日志', async () => {
+    const commitStep = jest.fn().mockResolvedValue({
+      runId: 'run-1',
+      stepKey: 'students',
+      status: 'conflict',
+      created: 0,
+      updated: 0,
+      skipped: 0,
+      failed: 0,
+      total: 0,
+      nextStepKey: null,
+      runStatus: 'ready',
+      message: '请先完成前置阶段',
+    });
+    const opLog = { log: jest.fn().mockResolvedValue(undefined) };
+    const controller = new ImportsController({ commitStep } as never, opLog as never);
+
+    await controller.commit(
+      principalRequest as never,
+      'run-1',
+      'transfers',
+      { decisions: [] },
+    );
+
+    expect(opLog.log).not.toHaveBeenCalled();
+  });
+});