refactor: modernize test structure and Jest configuration

- Move component tests to co-located __tests__ directories
- Rename test files to follow .test.js/.test.jsx convention
- Simplify Jest testMatch patterns using glob syntax
- Remove empty .keep files from unused test directories

Author: jorilindell

jest.config.js

@@ -3,8 +3,7 @@ module.exports = {
   testEnvironment: 'jsdom',
   setupFilesAfterEnv: ['<rootDir>/test/setupTests.js'],
   testMatch: [
-    '<rootDir>/test/**/*.test.js',
-    '<rootDir>/test/**/*Test.js'
+    '<rootDir>/{test,src}/**/__tests__/*.test.{js,jsx}'
   ],
   moduleFileExtensions: ['js', 'jsx'],
   transform: {

test/components/MainTest.js src/components/__tests__/Main.test.jsxtest/components/MainTest.js renamed to src/components/__tests__/Main.test.jsx

@@ -1,4 +1,3 @@
-/*eslint-env node, jest */
 /*eslint no-console: 0*/
 'use strict';