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/taskworker.js

@@ -1,26 +1,25 @@
 #!/usr/bin/env -S node --unhandled-rejections=strict
 
-'use strict';
-
-const apptask = require('./apptask.js'),
-    backupCleaner = require('./backupcleaner.js'),
-    backupIntegrity = require('./backupintegrity.js'),
-    backuptask = require('./backuptask.js'),
-    BoxError = require('./boxerror.js'),
-    dashboard = require('./dashboard.js'),
-    database = require('./database.js'),
-    dns = require('./dns.js'),
-    dyndns = require('./dyndns.js'),
-    externalLdap = require('./externalldap.js'),
-    fs = require('node:fs'),
-    locks = require('./locks.js'),
-    mailServer = require('./mailserver.js'),
-    net = require('node:net'),
-    reverseProxy = require('./reverseproxy.js'),
-    safe = require('safetydance'),
-    tasks = require('./tasks.js'),
-    timers = require('timers/promises'),
-    updater = require('./updater.js');
+import * as apptask from './apptask.js';
+import * as backupCleaner from './backupcleaner.js';
+import * as backupIntegrity from './backupintegrity.js';
+import * as backuptask from './backuptask.js';
+import BoxError from './boxerror.js';
+import * as dashboard from './dashboard.js';
+import * as database from './database.js';
+import * as dns from './dns.js';
+import * as dyndns from './dyndns.js';
+import * as externalLdap from './externalldap.js';
+import fs from 'node:fs';
+import locks from './locks.js';
+import * as mailServer from './mailserver.js';
+import net from 'node:net';
+import * as reverseProxy from './reverseproxy.js';
+import safe from 'safetydance';
+import tasks from './tasks.js';
+import timers from 'timers/promises';
+import * as updater from './updater.js';
+import debugModule from 'debug';
 
 const TASKS = { // indexed by task type
     app: apptask.run,
@@ -101,7 +100,7 @@ async function main() {
         return process.exit(50);
     }
 
-    const debug = require('debug')('box:taskworker'); // require this here so that logging handler is already setup
+    const debug = debugModule('box:taskworker'); // import this here so that logging handler is already setup
 
     process.on('SIGTERM', () => {
         debug('Terminated');