chore: rename to arcanesync-backend; update agents.md; disable vitest in eslint

eslint.config.mjs

@@ -6,9 +6,13 @@ export default antfu({
     quotes: 'single',
   },
   typescript: true,
+  // project uses node --test, not vitest
+  vitest: false,
   ignores: ['.omc', 'src/db/migrations'],
   rules: {
     'no-console': 'off',
     'antfu/no-top-level-await': 'off',
+    // project uses node --test, not vitest
+    'test/no-import-node-test': 'off',
   },
 })