Name the default exports in eslint.config.mjs and postcss.config.mjs #59

Problem

Both config files export default an anonymous array/object, which trips import/no-anonymous-default-export:

• eslint.config.mjs
• postcss.config.mjs:1

Done when

• Each assigns to a named const first (const eslintConfig = [...]; export default eslintConfig;).
• npm run lint and npm run build still pass, and the site's styles are unchanged (PostCSS still runs Tailwind).

Size: ~4 lines.

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