Convert backend to ESM

- About 5 years overdue
- Remove eslint, use bomejs instead

backend/migrate.js

@@ -1,15 +1,13 @@
-const db     = require('./db');
-const logger = require('./logger').migrate;
+import db from "./db.js";
+import { migrate as logger } from "./logger.js";
 
-module.exports = {
-	latest: function () {
-		return db.migrate.currentVersion()
-			.then((version) => {
-				logger.info('Current database version:', version);
-				return db.migrate.latest({
-					tableName: 'migrations',
-					directory: 'migrations'
-				});
-			});
-	}
+const migrateUp = async () => {
+	const version = await db.migrate.currentVersion();
+	logger.info("Current database version:", version);
+	return await db.migrate.latest({
+		tableName: "migrations",
+		directory: "migrations",
+	});
 };
+
+export { migrateUp };