Add rivals support for Lapistoria-peace

Fix stamp not properly initialized on usaneko

popn@asphyxia/handler/utils.ts

@@ -1,5 +1,5 @@
 import { Achievements } from "../models/achievements";
-import { Profile, Scores, ExtraData, Params } from "../models/common";
+import { Profile, Scores, ExtraData, Params, Rivals } from "../models/common";
 
 const CURRENT_DATA_VERSION = 2;
 
@@ -68,6 +68,11 @@ export const writeProfile = async (refid: string, profile: Profile) => {
     await DB.Upsert<Profile>(refid, { collection: 'profile' }, profile);
 }
 
+export const readRivals = async (refid: string): Promise<Rivals> => {
+    const rivals = await DB.FindOne<Rivals>(refid, { collection: 'rivals' });
+    return rivals || { collection: 'rivals', rivals: [] };
+}
+
 export const readParams = async (refid: string, version: string): Promise<Params> => {
     const params = await DB.FindOne<Params>(refid, { collection: 'params', version });
     return params || { collection: 'params', version, params: {} };