refactor: refactoring imports

将来ESMに移行しやすいように
Related: #7658

なんかmochaが起動しなくなってるけど理由不明
すぐ直したい

src/tools/demote-admin.ts

@@ -1,6 +1,6 @@
-import { initDb } from '../db/postgre';
+import { initDb } from '../db/postgre.js';
 import { getRepository } from 'typeorm';
-import { User } from '../models/entities/user';
+import { User } from '@/models/entities/user.js';
 
 async function main(username: string) {
 	if (!username) throw `username required`;