core&ui: add homework files & enhance delete operation (#755)

packages/hydrooj/src/handler/contest.ts

@@ -515,6 +515,7 @@ export class ContestEditHandler extends Handler {
             ScheduleModel.deleteMany({
                 type: 'schedule', subType: 'contest', domainId, tid,
             }),
+            storage.del(this.tdoc.files?.map((i) => `contest/${domainId}/${tid}/${i.name}`) || [], this.user._id),
         ]));
         this.response.redirect = this.url('contest_main');
     }