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/ldapserver.js

@@ -1,27 +1,33 @@
-'use strict';
+import * as addonConfigs from './addonconfigs.js';
+import assert from 'node:assert';
+import apps from './apps.js';
+import AuditSource from './auditsource.js';
+import BoxError from './boxerror.js';
+import constants from './constants.js';
+import debugModule from 'debug';
+import eventlog from './eventlog.js';
+import * as groups from './groups.js';
+import ldap from 'ldapjs';
+import * as mail from './mail.js';
+import safe from 'safetydance';
+import * as users from './users.js';
+import util from 'node:util';
 
-exports = module.exports = {
+const debug = debugModule('box:ldapserver');
+
+let _MOCK_APP = null;
+
+function _setMockApp(app) {
+    _MOCK_APP = app;
+}
+
+export {
     start,
     stop,
-
-    _MOCK_APP: null
+    _MOCK_APP,
+    _setMockApp,
 };
 
-const addonConfigs = require('./addonconfigs.js'),
-    assert = require('node:assert'),
-    apps = require('./apps.js'),
-    AuditSource = require('./auditsource.js'),
-    BoxError = require('./boxerror.js'),
-    constants = require('./constants.js'),
-    debug = require('debug')('box:ldapserver'),
-    eventlog = require('./eventlog.js'),
-    groups = require('./groups.js'),
-    ldap = require('ldapjs'),
-    mail = require('./mail.js'),
-    safe = require('safetydance'),
-    users = require('./users.js'),
-    util = require('node:util');
-
 let gServer = null;
 
 const NOOP = function () {};
@@ -33,7 +39,7 @@ async function authenticateApp(req, res, next) {
 
     // this is only used by the ldap test. the apps tests still uses proper docker
     if (constants.TEST && sourceIp === '127.0.0.1') {
-        req.app = exports._MOCK_APP;
+        req.app = _MOCK_APP;
         return next();
     }