feat(ai-chat): AI 导入确认流程完善并清理代码质量

- 新增导入确认/映射解析辅助，支持预检后生成导入向导
- 抽取 parseAttachmentArgs/beginImportToolRun 等重复逻辑
- 双重类型断言改为运行时守卫，消除 aislop 告警

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

@@ -58,7 +58,9 @@ import {
 } from './ai-chat.streaming';
 import {
   resolveFormConversationId,
+  resolvePreflightConversationId,
   resolveReviewConversationId,
+  resolveImportPreflight,
   submitForm,
   submitReview,
   confirmReviewStep,
@@ -297,10 +299,10 @@ export class AiChatService implements AiChatServiceContext {
   executePreflightImport(
     messageId: number,
     call: ModelToolCall,
-    userId: number,
+    context: ReturnType<typeof AgentToolContextFactory.fromAuthenticatedUser>,
     emit: AiSseEmitter,
   ): Promise<string> {
-    return executePreflightImport(this, messageId, call, userId, emit);
+    return executePreflightImport(this, messageId, call, context, emit);
   }
 
   executeGeneration(input: GenerationInput): Promise<void> {
@@ -407,6 +409,10 @@ export class AiChatService implements AiChatServiceContext {
     return resolveReviewConversationId(this, userId, reviewId);
   }
 
+  resolvePreflightConversationId(userId: number, messageId: number): Promise<number> {
+    return resolvePreflightConversationId(this, userId, messageId);
+  }
+
   submitForm(
     user: AuthenticatedUser,
     formId: string,
@@ -433,6 +439,21 @@ export class AiChatService 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,