fix: preserve lint migration contracts

eslint.format.config.mjs

@@ -0,0 +1,51 @@
+import stylistic from '@stylistic/eslint-plugin'
+import parser from '@typescript-eslint/parser'
+
+// Oxlint's JavaScript-plugin compatibility layer reports these rules but does
+// not execute their fixers. Keep this config formatting-only: Oxlint remains
+// the authoritative repository linter after this pass applies safe fixes.
+export default [
+  {
+    ignores: [
+      '**/lib/**',
+      '**/node_modules/**',
+      '**/.sessions/**',
+      '.claude/**',
+      '**/.doc-typecheck-*/**',
+      '**/.node-next-types-*/**',
+      'website/.generated/**',
+      'vendor/**',
+      'native/**',
+      '**/*.js',
+      '**/*.mjs',
+      '**/*.config.ts',
+      'packages/client/tsdown.client.ts',
+    ],
+  },
+  {
+    files: ['**/*.{ts,tsx,mts,cts}'],
+    languageOptions: {
+      parser,
+      parserOptions: {
+        sourceType: 'module',
+      },
+    },
+    plugins: {
+      '@stylistic': stylistic,
+    },
+    rules: {
+      '@stylistic/indent': ['error', 2],
+      '@stylistic/semi': ['error', 'never'],
+      '@stylistic/quotes': ['error', 'single', { avoidEscape: true }],
+      '@stylistic/comma-dangle': ['error', 'always-multiline'],
+      '@stylistic/eol-last': ['error', 'always'],
+      '@stylistic/no-trailing-spaces': 'error',
+      '@stylistic/object-curly-spacing': ['error', 'always'],
+      '@stylistic/arrow-parens': ['error', 'as-needed', { requireForBlockBody: true }],
+      '@stylistic/member-delimiter-style': ['error', {
+        multiline: { delimiter: 'none' },
+        singleline: { delimiter: 'semi', requireLast: false },
+      }],
+    },
+  },
+]