fix(build): Convert tailwind config to CJS

- Renamed tailwind.config.ts to .cjs to force CommonJS loading
- Switched to require() syntax to bypass ESM loader issues in PostCSS

frontend/tailwind.config.cjs

@@ -1,7 +1,7 @@
-import colors from 'tailwindcss/colors';
+const colors = require('tailwindcss/colors');
 
 /** @type {import('tailwindcss').Config} */
-export default {
+module.exports = {
     content: [
         "./index.html",
         "./src/**/*.{js,ts,jsx,tsx}",
@@ -193,5 +193,5 @@ export default {
         },
     },
 },
-plugins: [],
+    plugins: [],
 }