refactor: migrate ESLint configuration to flat config and remove redundant rule files

- replace legacy .eslintrc files with flat eslint.config.js
- consolidate eslint globals for improved code clarity
- enable prefer-const and no-unused-vars off in *.js for flexibility
- remove unused import statements and redundant eslint directives from epic-games.js and aliexpress.js
- standardize function parameter syntax to arrow with parentheses omitted where safe
- add comments marking unused but retained functions for reference

.eslintrc.cjs

@@ -0,0 +1,45 @@
+module.exports = {
+  env: {
+    node: true,
+    es2021: true,
+    es6: true,
+  },
+  extends: [
+    'eslint:recommended',
+  ],
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+  },
+  rules: {
+    'no-unused-vars': ['warn', {
+      varsIgnorePattern: '^_',
+      argsIgnorePattern: '^_',
+    }],
+    'no-undef': 'error',
+    '@stylistic/js/comma-dangle': ['error', 'always-multiline'],
+    '@stylistic/js/arrow-parens': ['error', 'as-needed'],
+  },
+  plugins: [
+    '@stylistic/js',
+  ],
+  globals: {
+    screenshot: 'readonly',
+    cfg: 'readonly',
+    URL_CLAIM: 'readonly',
+    COOKIES_PATH: 'readonly',
+    BEARER_TOKEN_NAME: 'readonly',
+    notify: 'readonly',
+    authenticator: 'readonly',
+    prompt: 'readonly',
+    html_game_list: 'readonly',
+    datetime: 'readonly',
+    filenamify: 'readonly',
+    handleSIGINT: 'readonly',
+    stealth: 'readonly',
+    jsonDb: 'readonly',
+    delay: 'readonly',
+    dataDir: 'readonly',
+    resolve: 'readonly',
+  },
+};