Feat/adds the no-window-eq-undefined ESLint rule to @docusaurus/eslint-plugin.

[webdevpraveen]

Summary

Adds the no-window-eq-undefined ESLint rule to @docusaurus/eslint-plugin.

Closes #6472

Motivation

Using typeof window !== 'undefined' is a common pattern for SSR escape hatching in React apps, but it is the wrong approach in Docusaurus. Docusaurus provides purpose-built APIs — useIsBrowser() and ExecutionEnvironment.canUseDOM — which integrate correctly with its SSR/pre-rendering pipeline.

This implements the no-window-eq-undefined rule originally proposed in #6472. (The string-literal-i18n-messages rule from the same issue was implemented in #7206, but this rule was never added.)

Changes

• packages/eslint-plugin/src/rules/no-window-eq-undefined.ts — new rule implementation
• packages/eslint-plugin/src/rules/__tests__/no-window-eq-undefined.test.ts — rule tests
• packages/eslint-plugin/src/index.ts — register rule + add to all config
• website/docs/api/misc/eslint-plugin/no-window-eq-undefined.mdx — documentation page
• website/docs/api/misc/eslint-plugin/README.mdx — add to supported rules table

Test Plan

yarn jest packages/eslint-plugin — all tests pass including new rule tests.

Rule Behavior

Flagged (incorrect pattern)

if (typeof window !== 'undefined') { ... }
const isBrowser = typeof window === 'undefined';
'undefined' !== typeof window  // reversed operands also caught

Not flagged (correct Docusaurus patterns)

import useIsBrowser from '@docusaurus/useIsBrowser';
const isBrowser = useIsBrowser();

import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
if (ExecutionEnvironment.canUseDOM) { ... }

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[slorber]

Thanks, but I don't think we need this, at least not in the form it is currently designed

Please respect my comment here, you clearly saw it and still sent a PR anyway: #6472 (comment)

Also, please disclose AI usage as requested in our contribution guidelines