feat：完善网站活动报名信息

app/api/website/model/activity_join.go

@@ -0,0 +1,11 @@
+package model
+
+import "SciencesServer/app/common/model"
+
+type ActivityJoin struct {
+	*model.ActivityJoin
+}
+
+func NewActivityJoin() *ActivityJoin {
+	return &ActivityJoin{model.NewActivityJoin()}
+}