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/app.module.ts

@@ -18,6 +18,7 @@ import { AddA2UiForms1784870000000 } from './migrations/1784870000000-AddA2UiFor
 import { AddA2UiReviews1784880000000 } from './migrations/1784880000000-AddA2UiReviews';
 import { AddImportRuns1784910000000 } from './migrations/1784910000000-AddImportRuns';
 import { DropAiMessageFeedback1784920000000 } from './migrations/1784920000000-DropAiMessageFeedback';
+import { AddImportRunSettings1784930000000 } from './migrations/1784930000000-AddImportRunSettings';
 const allMigrations = [
   InitialSchema1784520727860,
   AddExamManagement1784600000000,
@@ -29,6 +30,7 @@ const allMigrations = [
   AddA2UiReviews1784880000000,
   AddImportRuns1784910000000,
   DropAiMessageFeedback1784920000000,
+  AddImportRunSettings1784930000000,
 ];
 import { AuthorizationModule } from './authorization';
 import { RbacModule } from './rbac/rbac.module';