Migrate codebase from CommonJS to ES Modules

- Convert all require()/module.exports to import/export across 260+ files
- Add "type": "module" to package.json to enable ESM by default
- Add migrations/package.json with "type": "commonjs" to keep db-migrate compatible
- Convert eslint.config.js to ESM with sourceType: "module"
- Replace __dirname/__filename with import.meta.dirname/import.meta.filename
- Replace require.main === module with process.argv[1] === import.meta.filename
- Remove 'use strict' directives (implicit in ESM)
- Convert dynamic require() in switch statements to static import lookup maps
  (dns.js, domains.js, backupformats.js, backupsites.js, network.js)
- Extract self-referencing exports.CONSTANT patterns into standalone const
  declarations (apps.js, services.js, locks.js, users.js, mail.js, etc.)
- Lazify SERVICES object in services.js to avoid circular dependency TDZ issues
- Add clearMailQueue() to mailer.js for ESM-safe queue clearing in tests
- Add _setMockApp() to ldapserver.js for ESM-safe test mocking
- Add _setMockResolve() wrapper to dig.js for ESM-safe DNS mocking in tests
- Convert backupupload.js to use dynamic imports so --check exits before
  loading the module graph (which requires BOX_ENV)
- Update check-install to use ESM import for infra_version.js
- Convert scripts/ (hotfix, release, remote_hotfix.js, find-unused-translations)
- All 1315 tests passing

Migration stats (AI-assisted using Cursor with Claude):
- Wall clock time: ~3-4 hours
- Assistant completions: ~80-100
- Estimated token usage: ~1-2M tokens

Co-authored-by: Cursor <cursoragent@cursor.com>

src/cron.js

@@ -1,4 +1,30 @@
-'use strict';
+import * as appHealthMonitor from './apphealthmonitor.js';
+import assert from 'node:assert';
+import * as appstore from './appstore.js';
+import AuditSource from './auditsource.js';
+import * as backupSites from './backupsites.js';
+import * as cloudron from './cloudron.js';
+import constants from './constants.js';
+import { CronJob } from 'cron';
+import debugModule from 'debug';
+import * as domains from './domains.js';
+import * as dyndns from './dyndns.js';
+import * as externalLdap from './externalldap.js';
+import eventlog from './eventlog.js';
+import * as janitor from './janitor.js';
+import * as mail from './mail.js';
+import * as metrics from './metrics.js';
+import * as network from './network.js';
+import * as oidcServer from './oidcserver.js';
+import paths from './paths.js';
+import * as reverseProxy from './reverseproxy.js';
+import safe from 'safetydance';
+import * as scheduler from './scheduler.js';
+import * as system from './system.js';
+import * as updater from './updater.js';
+import util from 'node:util';
+
+const debug = debugModule('box:cron');
 
 // IMPORTANT: These patterns are together because they spin tasks which acquire a lock
 // If the patterns overlap all the time, then the task may not ever get a chance to run!
@@ -6,7 +32,7 @@
 const DEFAULT_CLEANUP_BACKUPS_PATTERN = '00 30 1,3,5,23 * * *',
     DEFAULT_AUTOUPDATE_PATTERN = '00 00 1,3,5,23 * * *';
 
-exports = module.exports = {
+export {
     startJobs,
 
     stopJobs,
@@ -20,32 +46,6 @@ exports = module.exports = {
     DEFAULT_AUTOUPDATE_PATTERN,
 };
 
-const appHealthMonitor = require('./apphealthmonitor.js'),
-    assert = require('node:assert'),
-    appstore = require('./appstore.js'),
-    AuditSource = require('./auditsource.js'),
-    backupSites = require('./backupsites.js'),
-    cloudron = require('./cloudron.js'),
-    constants = require('./constants.js'),
-    { CronJob } = require('cron'),
-    debug = require('debug')('box:cron'),
-    domains = require('./domains.js'),
-    dyndns = require('./dyndns.js'),
-    externalLdap = require('./externalldap.js'),
-    eventlog = require('./eventlog.js'),
-    janitor = require('./janitor.js'),
-    mail = require('./mail.js'),
-    metrics = require('./metrics.js'),
-    network = require('./network.js'),
-    oidcServer = require('./oidcserver.js'),
-    paths = require('./paths.js'),
-    reverseProxy = require('./reverseproxy.js'),
-    safe = require('safetydance'),
-    scheduler = require('./scheduler.js'),
-    system = require('./system.js'),
-    updater = require('./updater.js'),
-    util = require('node:util');
-
 const gJobs = {
     autoUpdater: null,
     backups: new Map(),