Next gen style: ESLint Stylistic

[cwillisf]

Resolves

• Closes chore(deps): update dependency eslint to v9 #171
• Resolves POD-186

Proposed Changes

Primary change: implement new style rules based on ESLint Stylistic.

Supporting changes:

• Upgrade to eslint@^9
• Use new flat format required by eslint@^9
• Move flattened legacy configs into legacy/

Bonus changes:

• The new configurations can lint JS/TS embedded in MD and HTML files

Reason for Changes

1. Reduce the need for maintenance on these rules by outsourcing to ESLint Stylistic.
2. This adjusts our style to be much closer to what the cool kids are doing these days the dominant styles in the JS/TS development community.

Test Coverage

Tested on the files in this repository. I also created a temporary HTML file to verify that those rules work.

[Copilot]

Pull Request Overview

This PR implements a major update to the ESLint configuration by adopting the new flat config format required for eslint@^9 and integrating ESLint Stylistic rules. Key changes include the removal of legacy configuration files (release.config.js, react.js, node.js, index.js, es6.js), the addition of new config files under lib/ (for web, React, Node, and legacy support), and updates to documentation and commitlint config.

Reviewed Changes

Copilot reviewed 19 out of 21 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
release.config.js	Removed the legacy release configuration.
release.config.cjs	Added a new CommonJS release configuration file.
react.js & node.js	Removed legacy React and Node configurations.
lib/web.mjs	Introduces the web configuration using the new flat config format.
lib/shared/makeConfig.mjs	Provides a helper function to generate ESLint configurations with new plugins.
lib/react.mjs & lib/node.mjs	Added updated ESLint configurations for React and Node environments.
lib/legacy/*	Added legacy configurations split into separate files for React, Node, ES6, etc.
lib/index.mjs	New central export that utilizes makeConfig for production configs.
eslint.config.mjs	New flat config export file for ESLint.
commitlint.config.mjs	Updated commitlint config formatting.
README.md	Revised documentation to reflect ESLint upgrade and usage instructions.

Files not reviewed (2)

• .editorconfig: Language not supported
• package.json: Language not supported

Comments suppressed due to low confidence (1)

lib/shared/makeConfig.mjs:6

• Directly importing from an internal path of 'eslint-plugin-html' may be fragile if the package's internal structure changes. Consider using a documented public API or verifying that this path remains supported in future releases.

import htmlSettings from 'eslint-plugin-html/src/settings.js'