refactor(config): switch configuration files to CommonJS module syntax

- Updated jest.config.js, postcss.config.js, and tailwind.config.js to use CommonJS module.exports syntax for compatibility with Node.js environments.

worklenz-frontend/jest.config.js

@@ -1,4 +1,4 @@
-export default {
+module.exports = {
   setupFilesAfterEnv: ['<rootDir>/src/setupTests.ts'],
   moduleNameMapper: {
     '^@/(.*)$': '<rootDir>/src/$1',

worklenz-frontend/postcss.config.js

@@ -1,4 +1,4 @@
-export default {
+module.exports = {
   plugins: {
     tailwindcss: {},
     autoprefixer: {},

worklenz-frontend/tailwind.config.js

@@ -1,5 +1,5 @@
 /** @type {import('tailwindcss').Config} */
-export default {
+module.exports = {
   content: ['./src/**/*.{js,jsx,ts,tsx}'],
   theme: {
     extend: {},