Update to Next.js 16 and enhance ESLint configuration

- Migrated from Next.js 15 to Next.js 16, updating all related dependencies and configurations.
- Enhanced ESLint setup with stricter rules, expanded plugin support, and improved type-aware linting options.
- Archived middleware by renaming it to `middleware.disabled.ts` for potential future use.

frontend/eslint.config.mjs

@@ -1,18 +1,13 @@
-import { FlatCompat } from '@eslint/eslintrc';
-import path from 'path';
-import { fileURLToPath } from 'url';
+import nextPlugin from '@next/eslint-plugin-next';
+import tseslint from 'typescript-eslint';
+import reactPlugin from 'eslint-plugin-react';
+import reactHooks from 'eslint-plugin-react-hooks';
+import jsxA11y from 'eslint-plugin-jsx-a11y';
 
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = path.dirname(__filename);
+const nextCoreWebVitalsRules = nextPlugin.configs['core-web-vitals']?.rules ?? {};
 
-const compat = new FlatCompat({
-  baseDirectory: __dirname,
-});
-
-const eslintConfig = [
-  ...compat.extends('next/core-web-vitals'),
-  ...compat.extends('next/typescript'),
-  ...compat.extends('prettier'), // Disable ESLint rules that conflict with Prettier
+export default [
+  // Ignores
   {
     ignores: [
       'node_modules/**',
@@ -25,8 +20,43 @@ const eslintConfig = [
       '*.gen.ts',
       '*.gen.tsx',
       'next-env.d.ts', // Auto-generated by Next.js
+      'eslint.config.mjs', // Do not lint the ESLint config itself
     ],
   },
+
+  // TypeScript recommended (non-type-checked) rules for broader compatibility
+  ...tseslint.configs.recommended,
+
+  // If you want type-aware linting, uncomment below and switch to `recommendedTypeChecked`
+  // {
+  //   files: ['**/*.{ts,tsx}'],
+  //   languageOptions: {
+  //     parserOptions: {
+  //       project: ['./tsconfig.json'],
+  //       tsconfigRootDir: new URL('.', import.meta.url).pathname,
+  //     },
+  //   },
+  // },
+
+  // Next.js + React rules (Core Web Vitals)
+  {
+    files: ['**/*.{js,jsx,ts,tsx}'],
+    plugins: {
+      '@next/next': nextPlugin,
+      react: reactPlugin,
+      'react-hooks': reactHooks,
+      'jsx-a11y': jsxA11y,
+    },
+    settings: {
+      react: {
+        version: 'detect',
+      },
+    },
+    rules: {
+      ...nextCoreWebVitalsRules,
+    },
+  },
+
   // Base rules for source code
   {
     files: ['src/**/*.{ts,tsx}'],
@@ -50,6 +80,7 @@ const eslintConfig = [
       ],
     },
   },
+
   // Relaxed rules for test files
   {
     files: ['tests/**/*.{ts,tsx}', '**/*.test.{ts,tsx}', '**/*.spec.{ts,tsx}'],
@@ -68,6 +99,7 @@ const eslintConfig = [
       ],
     },
   },
+
   // Relaxed rules for E2E tests
   {
     files: ['e2e/**/*.{ts,tsx}'],
@@ -83,6 +115,7 @@ const eslintConfig = [
       ],
     },
   },
+
   // Relaxed rules for scripts and config files
   {
     files: ['scripts/**/*.{ts,js}', '*.config.{ts,js,mjs}', 'jest.setup.js'],
@@ -101,5 +134,3 @@ const eslintConfig = [
     },
   },
 ];
-
-export default eslintConfig;