支持访客实时输入草稿展示与联系方式自动识别

坐席输入框上方显示「对方正在输入」草稿；从草稿/消息提取手机微信邮箱QQ并追加入库，不覆盖已有联系方式。

server/internal/handler/customer.go

@@ -79,8 +79,13 @@ func (h *CustomerHandler) Get(c *gin.Context) {
 		sessionQuery = sessionQuery.Where("agent_id = ?", middleware.GetUserID(c))
 	}
 	sessionQuery.Order("created_at desc").Limit(20).Find(&sessions)
+	contacts := listCustomerContacts(customer.ID)
 
-	middleware.JSON(c, gin.H{"customer": customer, "sessions": sessions})
+	middleware.JSON(c, gin.H{
+		"customer": customer,
+		"sessions": sessions,
+		"contacts": contacts,
+	})
 }
 
 func (h *CustomerHandler) Create(c *gin.Context) {