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/docker.js

@@ -1,6 +1,26 @@
-'use strict';
+import apps from './apps.js';
+import assert from 'node:assert';
+import BoxError from './boxerror.js';
+import constants from './constants.js';
+import * as dashboard from './dashboard.js';
+import debugModule from 'debug';
+import Docker from 'dockerode';
+import * as dockerRegistries from './dockerregistries.js';
+import fs from 'node:fs';
+import * as mailServer from './mailserver.js';
+import os from 'node:os';
+import paths from './paths.js';
+import promiseRetry from './promise-retry.js';
+import services from './services.js';
+import shellModule from './shell.js';
+import safe from 'safetydance';
+import timers from 'timers/promises';
+import * as volumes from './volumes.js';
 
-exports = module.exports = {
+const debug = debugModule('box:docker');
+const shell = shellModule('docker');
+
+export {
     ping,
 
     info,
@@ -31,25 +51,6 @@ exports = module.exports = {
     resizeExec
 };
 
-const apps = require('./apps.js'),
-    assert = require('node:assert'),
-    BoxError = require('./boxerror.js'),
-    constants = require('./constants.js'),
-    dashboard = require('./dashboard.js'),
-    debug = require('debug')('box:docker'),
-    Docker = require('dockerode'),
-    dockerRegistries = require('./dockerregistries.js'),
-    fs = require('node:fs'),
-    mailServer = require('./mailserver.js'),
-    os = require('node:os'),
-    paths = require('./paths.js'),
-    promiseRetry = require('./promise-retry.js'),
-    services = require('./services.js'),
-    shell = require('./shell.js')('docker'),
-    safe = require('safetydance'),
-    timers = require('timers/promises'),
-    volumes = require('./volumes.js');
-
 const gConnection = new Docker({ socketPath: paths.DOCKER_SOCKET_PATH });
 
 const CLOUDRON_REGISTRIES = [ 'registry.docker.com', 'registry.ipv4.docker.com', 'quay.io' ]; // order determines priority and is important!