v1.0.0: Add JS/TS configuration exports; switch Babel plugins

⚠️ BREAKING CHANGES (if using lint rules)

• Transition from deprecated @babel/plugin-syntax-import-assertions to the new @babel/plugin-syntax-import-attributes and enable option deprecatedAssertSyntax for backward compatibility with import assertions. Since this is a peer dependency, consumers must switch plugins to match.

🌎 External changes

• Export JavaScript configuration as configuration/javascript.
• Export TypeScript configuration as configuration/typescript now that microsoft/TypeScript#48665 has been fixed.
• Update README with instructions on how to consume Babel, ESLint, JavaScript, rollup.js, and TypeScript configurations.

🏠 Internal changes

• Clean up package.json scripts and remove engines field.

🧹 Chores

• Upgrade dependencies.