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/dashboard.js

@@ -1,39 +1,38 @@
-'use strict';
+import apps from './apps.js';
+import * as appstore from './appstore.js';
+import assert from 'node:assert';
+import BoxError from './boxerror.js';
+import * as branding from './branding.js';
+import constants from './constants.js';
+import debugModule from 'debug';
+import * as dns from './dns.js';
+import * as externalLdap from './externalldap.js';
+import eventlog from './eventlog.js';
+import Location from './location.js';
+import * as mailServer from './mailserver.js';
+import * as platform from './platform.js';
+import * as reverseProxy from './reverseproxy.js';
+import safe from 'safetydance';
+import * as settings from './settings.js';
+import * as system from './system.js';
+import tasks from './tasks.js';
+import * as userDirectory from './user-directory.js';
 
-exports = module.exports = {
+const debug = debugModule('box:dashboard');
+
+const _setLocation = setLocation;
+
+export {
     getLocation,
     clearLocation,
-
-    startPrepareLocation, // starts the task
-    prepareLocation,      // the task to setup dns and cert
-    setupLocation,        // initial setup from setup/restore
-    changeLocation,       // only on dashboard change (post setup/restore)
-
+    startPrepareLocation, // starts the task,
+    prepareLocation,      // the task to setup dns and cert,
+    setupLocation,        // initial setup from setup/restore,
+    changeLocation,       // only on dashboard change (post setup/restore),
     getConfig,
-
-    _setLocation: setLocation,
+    _setLocation,
 };
 
-const apps = require('./apps.js'),
-    appstore = require('./appstore.js'),
-    assert = require('node:assert'),
-    BoxError = require('./boxerror.js'),
-    branding = require('./branding.js'),
-    constants = require('./constants.js'),
-    debug = require('debug')('box:dashboard'),
-    dns = require('./dns.js'),
-    externalLdap = require('./externalldap.js'),
-    eventlog = require('./eventlog.js'),
-    Location = require('./location.js'),
-    mailServer = require('./mailserver.js'),
-    platform = require('./platform.js'),
-    reverseProxy = require('./reverseproxy.js'),
-    safe = require('safetydance'),
-    settings = require('./settings.js'),
-    system = require('./system.js'),
-    tasks = require('./tasks.js'),
-    userDirectory = require('./user-directory.js');
-
 async function getLocation() {
     const domain = await settings.get(settings.DASHBOARD_DOMAIN_KEY);
     const subdomain = await settings.get(settings.DASHBOARD_SUBDOMAIN_KEY);