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/reverseproxy.js

@@ -1,6 +1,33 @@
-'use strict';
+import * as acme2 from './acme2.js';
+import apps from './apps.js';
+import assert from 'node:assert';
+import blobs from './blobs.js';
+import BoxError from './boxerror.js';
+import constants from './constants.js';
+import * as dashboard from './dashboard.js';
+import debugModule from 'debug';
+import * as dns from './dns.js';
+import * as docker from './docker.js';
+import * as domains from './domains.js';
+import ejs from 'ejs';
+import eventlog from './eventlog.js';
+import * as ipaddr from './ipaddr.js';
+import fs from 'node:fs';
+import Location from './location.js';
+import * as mailServer from './mailserver.js';
+import * as network from './network.js';
+import * as openssl from './openssl.js';
+import path from 'node:path';
+import paths from './paths.js';
+import safe from 'safetydance';
+import * as settings from './settings.js';
+import shellModule from './shell.js';
+import tasks from './tasks.js';
 
-exports = module.exports = {
+const debug = debugModule('box:reverseproxy');
+const shell = shellModule('reverseproxy');
+
+export {
     setUserCertificate, // per location certificate
     setFallbackCertificate, // per domain certificate
 
@@ -31,34 +58,8 @@ exports = module.exports = {
     setTrustedIps
 };
 
-const acme2 = require('./acme2.js'),
-    apps = require('./apps.js'),
-    assert = require('node:assert'),
-    blobs = require('./blobs.js'),
-    BoxError = require('./boxerror.js'),
-    constants = require('./constants.js'),
-    dashboard = require('./dashboard.js'),
-    debug = require('debug')('box:reverseproxy'),
-    dns = require('./dns.js'),
-    docker = require('./docker.js'),
-    domains = require('./domains.js'),
-    ejs = require('ejs'),
-    eventlog = require('./eventlog.js'),
-    ipaddr = require('./ipaddr.js'),
-    fs = require('node:fs'),
-    Location = require('./location.js'),
-    mailServer = require('./mailserver.js'),
-    network = require('./network.js'),
-    openssl = require('./openssl.js'),
-    path = require('node:path'),
-    paths = require('./paths.js'),
-    safe = require('safetydance'),
-    settings = require('./settings.js'),
-    shell = require('./shell.js')('reverseproxy'),
-    tasks = require('./tasks.js');
-
-const NGINX_APPCONFIG_EJS = fs.readFileSync(__dirname + '/nginxconfig.ejs', { encoding: 'utf8' });
-const RESTART_SERVICE_CMD = path.join(__dirname, 'scripts/restartservice.sh');
+const NGINX_APPCONFIG_EJS = fs.readFileSync(import.meta.dirname + '/nginxconfig.ejs', { encoding: 'utf8' });
+const RESTART_SERVICE_CMD = path.join(import.meta.dirname, 'scripts/restartservice.sh');
 
 function nginxLocation(s) {
     if (!s.startsWith('!')) return s;
@@ -393,7 +394,7 @@ async function writeDashboardNginxConfig(vhost, certificatePath) {
     assert.strictEqual(typeof certificatePath, 'object');
 
     const data = {
-        sourceDir: path.resolve(__dirname, '..'),
+        sourceDir: path.resolve(import.meta.dirname, '..'),
         vhost,
         hasIPv6: network.hasIPv6(),
         endpoint: 'dashboard',
@@ -451,7 +452,7 @@ async function writeAppLocationNginxConfig(app, location, certificatePath) {
     const { type, fqdn} = location;
 
     const data = {
-        sourceDir: path.resolve(__dirname, '..'),
+        sourceDir: path.resolve(import.meta.dirname, '..'),
         vhost: fqdn,
         hasIPv6: network.hasIPv6(),
         ip: null,
@@ -694,7 +695,7 @@ async function writeDefaultConfig(options) {
     }
 
     const data = {
-        sourceDir: path.resolve(__dirname, '..'),
+        sourceDir: path.resolve(import.meta.dirname, '..'),
         vhost: '',
         hasIPv6: network.hasIPv6(),
         endpoint: options.activated ? 'ip' : 'setup',