chore: migrate ESLint configuration to flat config without FlatCompat

Resolves #7906
- Replace FlatCompat blocks with native flat configs from @nx/eslint-plugin and typescript-eslint
- Remove @eslint/eslintrc and @eslint/js dependencies
- Add typescript-eslint for native flat config exports

eslint.config.cjs

@@ -1,19 +1,14 @@
-const { FlatCompat } = require('@eslint/eslintrc');
-const js = require('@eslint/js');
-const nxEslintPlugin = require('@nx/eslint-plugin');
+const nx = require('@nx/eslint-plugin');
 const storybook = require('eslint-plugin-storybook');
+const tseslint = require('typescript-eslint');
+const importPlugin = require('eslint-plugin-import');
 
-const compat = new FlatCompat({
-  baseDirectory: __dirname,
-  recommendedConfig: js.configs.recommended
-});
-
-module.exports = [
+module.exports = tseslint.config(
   {
     ignores: ['**/dist']
   },
   ...storybook.configs['flat/recommended'],
-  { plugins: { '@nx': nxEslintPlugin } },
+  { plugins: { '@nx': nx } },
   {
     files: ['**/*.ts', '**/*.tsx', '**/*.js', '**/*.jsx'],
     rules: {
@@ -35,41 +30,30 @@ module.exports = [
       'no-extra-semi': 'off'
     }
   },
-  ...compat
-    .config({
-      extends: ['plugin:@nx/typescript']
-    })
-    .map((config) => ({
+  ...nx.configs['flat/typescript'].map((config) => ({
     ...config,
     files: ['**/*.ts', '**/*.tsx', '**/*.cts', '**/*.mts'],
-      rules: {
-        ...config.rules
-      }
   })),
-  ...compat
-    .config({
-      extends: ['plugin:@nx/javascript']
-    })
-    .map((config) => ({
+  ...nx.configs['flat/javascript'].map((config) => ({
     ...config,
     files: ['**/*.js', '**/*.jsx', '**/*.cjs', '**/*.mjs'],
-      rules: {
-        ...config.rules
-      }
   })),
-  ...compat
-    .config({
-      plugins: ['eslint-plugin-import', '@typescript-eslint'],
-      extends: [
-        'plugin:@typescript-eslint/recommended-type-checked',
-        'plugin:@typescript-eslint/stylistic-type-checked'
-      ]
-    })
-    .map((config) => ({
-      ...config,
+  {
     files: ['**/*.ts'],
+    extends: [
+      ...tseslint.configs.recommendedTypeChecked,
+      ...tseslint.configs.stylisticTypeChecked
+    ],
+    plugins: {
+      import: importPlugin
+    },
+    languageOptions: {
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: __dirname
+      }
+    },
     rules: {
-        ...config.rules,
       '@typescript-eslint/consistent-indexed-object-style': 'off',
       '@typescript-eslint/dot-notation': 'off',
       '@typescript-eslint/explicit-member-accessibility': [
@@ -190,5 +174,5 @@ module.exports = [
       // and can be remove once solved
       '@typescript-eslint/prefer-nullish-coalescing': 'warn' // TODO: Requires strictNullChecks: true
     }
-    }))
-];
+  }
+);

package.json

@@ -166,8 +166,6 @@
     "@angular/language-service": "22.1.2",
     "@angular/localize": "22.1.2",
     "@angular/pwa": "22.1.4",
-    "@eslint/eslintrc": "3.3.1",
-    "@eslint/js": "9.35.0",
     "@nestjs/schematics": "11.1.0",
     "@nestjs/testing": "11.2.3",
     "@nx/angular": "23.1.1",
@@ -221,6 +219,7 @@
     "ts-node": "10.9.2",
     "tslib": "2.8.1",
     "typescript": "6.0.3",
+    "typescript-eslint": "8.67.0",
     "webpack-cli": "7.1.0"
   },
   "engines": {