center: add notification push support

packages/center/index.ts

@@ -63,6 +63,7 @@ class DataReportHandler extends Handler {
             sandbox: payload.sandbox,
             dbVersion: payload.dbVersion,
         };
+        if (old.notification) setPayload.notification = '';
         if (old && lt(payload.version, old.version)) {
             await coll.updateOne(
                 { _id: installId },
@@ -85,6 +86,7 @@ class DataReportHandler extends Handler {
         this.ctx.emit('center/report', this, installId, old, payload);
         // TODO deliver messages
         this.response.body = { code: 0 };
+        if (old.notification) this.response.body.notification = old.notification;
     }
 }