refactor: migrate to eslint flat config and format codebase with prettier

- Remove legacy .eslintrc.cjs and .eslintignore
- Add eslint.config.js with flat config, security rules (no-eval, no-implied-eval, no-new-func, no-script-url)
- Add .prettierrc and .prettierignore
- Format entire codebase with prettier

eslint.config.js

@@ -0,0 +1,48 @@
+import js from '@eslint/js'
+import globals from 'globals'
+import reactHooks from 'eslint-plugin-react-hooks'
+import reactRefresh from 'eslint-plugin-react-refresh'
+import tseslint from 'typescript-eslint'
+import eslintConfigPrettier from 'eslint-config-prettier'
+
+export default tseslint.config(
+  {
+    ignores: ['dist', 'node_modules', 'public'],
+  },
+  {
+    files: ['**/*.{ts,tsx}'],
+    extends: [
+      js.configs.recommended,
+      ...tseslint.configs.recommended,
+    ],
+    languageOptions: {
+      ecmaVersion: 2020,
+      globals: globals.browser,
+    },
+    plugins: {
+      'react-hooks': reactHooks,
+      'react-refresh': reactRefresh,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      'react-hooks/set-state-in-effect': 'off',
+      'react-hooks/static-components': 'off',
+      'react-hooks/immutability': 'off',
+      'react-hooks/refs': 'off',
+      'react-hooks/purity': 'off',
+      'react-hooks/variables': 'off',
+      'react-refresh/only-export-components': [
+        'warn',
+        { allowConstantExport: true },
+      ],
+      '@typescript-eslint/no-explicit-any': 'warn',
+      '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_' }],
+      'no-empty': 'warn',
+      'no-eval': 'error',
+      'no-implied-eval': 'error',
+      'no-new-func': 'error',
+      'no-script-url': 'error',
+    },
+  },
+  eslintConfigPrettier,
+)