test: install framework registry once via mocha require, drop per-test setup

Same idea as codeceptjs's own \`config.require\` option: list a setup
script in mocha's config and let it run once before any test. The
unit-test world is the only place that needs to fake \`globalThis.codeceptjs\`
(unit tests bypass the runner that normally installs it), so park the
five lines there and stop sprinkling them into individual test files.

- test/support/setup.mjs — was just chai.should(); now also installs
  the framework registry (Config, container, event, output, recorder,
  Helper) on globalThis.codeceptjs the same way lib/codecept.js does
  for the live runner.
- .mocharc.mjs → .mocharc.cjs — mocha's config auto-discovery is
  inconsistent with .mocharc.mjs across CLI shapes (recursive runs picked
  it up, single-file runs didn't). The CJS form auto-loads reliably
  whether you point mocha at a directory or a single file. The exposed
  config is unchanged: \`require\` + \`extension\`.
- test/unit/plugin/browser_test.js — drop the per-test inline
  \`globalThis.codeceptjs = ...\`; setup.mjs now covers it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: DavertMik

.mocharc.cjs

@@ -0,0 +1,6 @@
+const path = require('path')
+
+module.exports = {
+  require: [path.join(__dirname, 'test', 'support', 'setup.mjs')],
+  extension: ['js', 'mjs'],
+}

.mocharc.mjs

@@ -1,2 +1,17 @@
 import * as chai from 'chai'
-chai.should()
+chai.should()
+
+// Install the framework registry the same way the runner does in lib/codecept.js.
+// Unit tests import lib/* modules directly (bypassing the runner), so without
+// this companion packages reaching for `globalThis.codeceptjs` (e.g.
+// @codeceptjs/configure inside the browser plugin) get an undefined handle.
+import Helper from '@codeceptjs/helper'
+import Config from '../../lib/config.js'
+import container from '../../lib/container.js'
+import event from '../../lib/event.js'
+import output from '../../lib/output.js'
+import recorder from '../../lib/recorder.js'
+
+if (!globalThis.codeceptjs) {
+  globalThis.codeceptjs = { config: Config, container, event, output, recorder, Helper }
+}

test/support/setup.mjs

@@ -1,16 +1,6 @@
 import { expect } from 'chai'
-import Config from '../../../lib/config.js'
-import container from '../../../lib/container.js'
-import event from '../../../lib/event.js'
-import output from '../../../lib/output.js'
-import recorder from '../../../lib/recorder.js'
-
-// This test imports the plugin directly, bypassing the runner. The runner
-// (lib/codecept.js) is what normally installs globalThis.codeceptjs so that
-// @codeceptjs/configure can reach framework singletons; do the same here.
-globalThis.codeceptjs = { config: Config, container, event, output, recorder }
-
 import browser from '../../../lib/plugin/browser.js'
+import Config from '../../../lib/config.js'
 
 async function applyAndCreate(args, base = {}) {
   Config.reset()