feat(migrate): enhance node version detection to include Volta in package.json

Author: naokihaba

packages/cli/src/migration/detector.ts

@@ -171,7 +171,6 @@ export function detectConfigs(projectPath: string): ConfigFiles {
 
   // Check package.json for "prettier" key and Volta node version
   const packageJsonPath = path.join(projectPath, 'package.json');
-
   if (fs.existsSync(packageJsonPath)) {
     try {
       const content = fs.readFileSync(packageJsonPath, 'utf8');

packages/cli/src/migration/migrator.ts

@@ -2083,6 +2083,8 @@ export type NodeVersionManagerDetection =
 
 /**
  * Detect a .nvmrc file in the project directory.
+ * If not found, check for a Volta node version in package.json.
+ * If either is found, return the relevant info for migration.
  * Returns undefined if not found or .node-version already exists.
  */
 export function detectNodeVersionManagerFile(