feat: migrate ESLint to v9 flat config

- Replace .eslintrc.json with eslint.config.mjs
- Simplify configuration using @antfu/eslint-config
- Add necessary ESLint plugin dependencies
- Disable overly strict style rules
- Set package.json type to module for ESM support
- Fix ESLint disable comment format

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

eslint.config.mjs

@@ -0,0 +1,67 @@
+import { combine, javascript, typescript, stylistic } from '@antfu/eslint-config'
+import globals from 'globals'
+import reactHooks from 'eslint-plugin-react-hooks'
+
+export default combine(
+  javascript({
+    overrides: {
+      'no-unused-vars': 'off',
+      'no-console': 'off',
+    },
+  }),
+
+  typescript(),
+
+  stylistic({
+    lessOpinionated: true,
+    jsx: false,
+    semi: false,
+    quotes: 'single',
+    overrides: {
+      'style/indent': ['error', 2],
+      'style/quotes': ['error', 'single'],
+      'style/max-statements-per-line': 'off',
+    },
+  }),
+
+  {
+    plugins: {
+      'react-hooks': reactHooks,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      'react-hooks/exhaustive-deps': 'warn',
+      'unused-imports/no-unused-vars': 'warn',
+      'unused-imports/no-unused-imports': 'warn',
+      '@typescript-eslint/no-use-before-define': 'off',
+      'ts/no-use-before-define': 'off',
+      'style/brace-style': 'off',
+    },
+  },
+
+  {
+    ignores: [
+      '**/node_modules/**',
+      '**/dist/**',
+      '**/build/**',
+      '**/out/**',
+      '**/.next/**',
+      '**/public/**',
+      '**/*.json',
+      'tailwind.config.js',
+      'next.config.js',
+    ],
+  },
+
+  {
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.es2025,
+        ...globals.node,
+        React: 'readable',
+        JSX: 'readable',
+      },
+    },
+  },
+)