feat(ai): 移除 Excel 导入预检链路

- 删除 preflight_import 工具、预检卡、resolve 接口与 ui.import_preflight 事件
- 删除 imports.preflight 解析器与 PreflightReport 类型
- SYSTEM_PROMPT 改为上传 Excel 后直接确认列映射/策略并调用 start_import_wizard
- 前端同步移除预检类型/组件/测试，保留导入向导

apps/server/src/ai-chat/ai-chat.service-base.ts

@@ -47,9 +47,7 @@ import {
 } from './ai-chat.streaming';
 import {
   resolveFormConversationId,
-  resolvePreflightConversationId,
   resolveReviewConversationId,
-  resolveImportPreflight,
   submitForm,
   submitReview,
   confirmReviewStep,
@@ -63,10 +61,7 @@ import {
   markReviewSubmittedOnMessage,
 } from './ai-chat.submissions';
 import { denyWriteTool, executeTool } from './ai-chat.tools';
-import {
-  executePreflightImport,
-  executeStartImportWizard,
-} from './ai-chat.tool-actions';
+import { executeStartImportWizard } from './ai-chat.tool-actions';
 export abstract class AiChatServiceBase implements AiChatServiceContext {
   readonly activeConversations = new Set<number>();
 
@@ -209,15 +204,6 @@ export abstract class AiChatServiceBase implements AiChatServiceContext {
     return executeStartImportWizard(this, messageId, call, context, emit);
   }
 
-  executePreflightImport(
-    messageId: number,
-    call: ModelToolCall,
-    context: ReturnType<typeof AgentToolContextFactory.fromAuthenticatedUser>,
-    emit: AiSseEmitter,
-  ): Promise<string> {
-    return executePreflightImport(this, messageId, call, context, emit);
-  }
-
   listConversations(userId: number): Promise<PublicConversation[]> {
     return listConversations(this, userId);
   }
@@ -318,10 +304,6 @@ export abstract class AiChatServiceBase implements AiChatServiceContext {
     return resolveReviewConversationId(this, userId, reviewId);
   }
 
-  resolvePreflightConversationId(userId: number, messageId: number): Promise<number> {
-    return resolvePreflightConversationId(this, userId, messageId);
-  }
-
   submitForm(
     user: AuthenticatedUser,
     formId: string,
@@ -348,21 +330,6 @@ export abstract class AiChatServiceBase implements AiChatServiceContext {
     return submitReview(this, user, reviewId, dto, signal, emit, onReady);
   }
 
-  resolveImportPreflight(
-    user: AuthenticatedUser,
-    messageId: number,
-    dto: {
-      clientRequestId: string;
-      mapping?: Record<string, unknown>;
-      settings?: Record<string, unknown>;
-    },
-    signal: AbortSignal,
-    emit: AiSseEmitter,
-    onReady: () => void,
-  ): Promise<void> {
-    return resolveImportPreflight(this, user, messageId, dto, signal, emit, onReady);
-  }
-
   confirmReviewStep(
     user: AuthenticatedUser,
     reviewId: string,