Implement existing API types

frontend-reactive/app/models/reaction.ts

@@ -0,0 +1,9 @@
+import Model, { attr } from '@ember-data/model'
+import type EmoteModel from './emote'
+
+export default class ReactionModel extends Model {
+  @attr declare noteId: string
+  @attr declare reactorId: string
+  @attr declare emoteId: number
+  @attr declare emote: EmoteModel
+}