fix: upgrade devDependencies and migrate to eslint 10 flat config

- Upgrade eslint 8.31 → 10.1 with new flat config (eslint.config.js)
- Upgrade @vercel/ncc 0.36 → 0.38.4
- Replace eslint-config-airbnb-base + eslint-plugin-import with @eslint/js + @stylistic/eslint-plugin
- Remove stale overrides in package.json (word-wrap, semver)
- Remove obsolete eslint-disable comments from source files
- Add { cause } to rethrown error in rsyncCli.js
- Add .gitignore and CLAUDE.md
- Resolves all 3 npm audit vulnerabilities (flatted, minimatch, js-yaml)

src/remoteCmd.js

@@ -11,7 +11,6 @@ const handleError = (message, isRequired, callback) => {
   }
 };
 
-// eslint-disable-next-line max-len
 const remoteCmd = async (content, privateKeyPath, isRequired, label) => new Promise((resolve, reject) => {
   const uuid = crypto.randomUUID();
   const filename = `local_ssh_script-${label}-${uuid}.sh`;