Refactor ESLint configuration and update test rules for clarity and consistency

- Consolidated and modularized `eslint.config.mjs` with defined rules for source, test, E2E, and scripts.
- Improved test and E2E rules with relaxed settings for flexibility and enhanced mocking.
- Standardized variable naming and removed redundant imports in unit and E2E tests.
- Updated error handling and comments to align with modern TypeScript best practices (e.g., `@ts-expect-error`).

frontend/eslint.config.mjs

@@ -9,7 +9,7 @@ const compat = new FlatCompat({
   baseDirectory: __dirname,
 });
 
-export default [
+const eslintConfig = [
   ...compat.extends('next/core-web-vitals'),
   ...compat.extends('next/typescript'),
   {
@@ -23,9 +23,12 @@ export default [
       'src/lib/api/generated/**',
       '*.gen.ts',
       '*.gen.tsx',
+      'next-env.d.ts', // Auto-generated by Next.js
     ],
   },
+  // Base rules for source code
   {
+    files: ['src/**/*.{ts,tsx}'],
     rules: {
       // Enforce Dependency Injection pattern for auth store
       // Components/hooks must use useAuth() from AuthContext, not useAuthStore directly
@@ -46,4 +49,56 @@ export default [
       ],
     },
   },
+  // Relaxed rules for test files
+  {
+    files: ['tests/**/*.{ts,tsx}', '**/*.test.{ts,tsx}', '**/*.spec.{ts,tsx}'],
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off', // Test mocks often need any
+      '@typescript-eslint/no-require-imports': 'off', // Jest sometimes needs require
+      'react/display-name': 'off', // Mock components don't need display names
+      'no-restricted-imports': 'off', // Tests can import store directly
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+        },
+      ],
+    },
+  },
+  // Relaxed rules for E2E tests
+  {
+    files: ['e2e/**/*.{ts,tsx}'],
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off', // Playwright helpers need flexibility
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+        },
+      ],
+    },
+  },
+  // Relaxed rules for scripts and config files
+  {
+    files: ['scripts/**/*.{ts,js}', '*.config.{ts,js,mjs}', 'jest.setup.js'],
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off', // Build scripts need flexibility
+      '@typescript-eslint/no-require-imports': 'off', // CommonJS configs
+      '@next/next/no-assign-module-variable': 'off', // Scripts may need module.exports
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+        },
+      ],
+    },
+  },
 ];
+
+export default eslintConfig;