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-attachment.service.ts

@@ -20,6 +20,8 @@ const ACCEPTED_MIME_TYPES = new Set([
   'image/png',
   'image/webp',
   'application/pdf',
+  'text/csv',
+  'application/csv',
   'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
   'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
   'application/vnd.openxmlformats-officedocument.presentationml.presentation',
@@ -210,6 +212,9 @@ export class AiAttachmentService {
       const result = await mammoth.extractRawText({ buffer });
       return this.normalizeExtractedText(result.value);
     }
+    if (mimeType.includes('csv')) {
+      return this.normalizeExtractedText(buffer.toString('utf8').replace(/^\uFEFF/, ''));
+    }
     if (mimeType.includes('spreadsheetml')) {
       return this.normalizeExtractedText(await this.excelReader.extractText(buffer));
     }
@@ -235,6 +240,7 @@ export class AiAttachmentService {
 
   private assertDeclaredType(declared: string, detected: string): void {
     if (!declared || declared === 'application/octet-stream') return;
+    if (detected.includes('csv') || declared.includes('csv')) return;
     if (declared !== detected) throw new BadRequestException('附件类型与文件内容不一致');
   }
 
@@ -245,6 +251,8 @@ export class AiAttachmentService {
       'image/png': ['png'],
       'image/webp': ['webp'],
       'application/pdf': ['pdf'],
+      'text/csv': ['csv'],
+      'application/csv': ['csv'],
       'application/vnd.openxmlformats-officedocument.wordprocessingml.document': ['docx'],
       'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': ['xlsx'],
       'application/vnd.openxmlformats-officedocument.presentationml.presentation': ['pptx'],
@@ -278,6 +286,7 @@ export class AiAttachmentService {
     ) {
       return declaredMimeType;
     }
+    if (/csv/i.test(declaredMimeType)) return 'text/csv';
     return 'application/octet-stream';
   }
 
@@ -305,6 +314,8 @@ export class AiAttachmentService {
       'image/png': 'png',
       'image/webp': 'webp',
       'application/pdf': 'pdf',
+      'text/csv': 'csv',
+      'application/csv': 'csv',
       'application/vnd.openxmlformats-officedocument.wordprocessingml.document': 'docx',
       'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': 'xlsx',
       'application/vnd.openxmlformats-officedocument.presentationml.presentation': 'pptx',