fix issues

server/ai/validator.js

@@ -1,5 +1,6 @@
 // JSON Schema 校验 — 验证 AI 返回的 JSON 结构
 const schemas = {
+  ask: { required: [], optional: ['question','reply'] },
   purchase: { required: ['purchase_item'], optional: ['quantity','unit_price','freight','payment_method','invoice_type','status','applicant','remarks','created_time','is_new','use_recent_image'] },
   query: { required: [], optional: [] },
   chat: { required: ['reply'], optional: [] },