Fix vite esm require error

[BoSuY0]

Fix Vite build error by migrating project to ES modules and updating TypeScript configuration.

The build failed with ERR_REQUIRE_ESM because the Vite configuration, PostCSS, and Tailwind config files were using CommonJS require() and module.exports syntax, while Vite 7 expects ES modules. This PR updates package.json to declare type: module, modifies tsconfig.node.json for ES module compatibility, and refactors postcss.config.js and tailwind.config.js to use import and export default.

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[cursor]

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