Upgrade Node.js runtime and support to latest LTS version

[Alicade123]

Description

Node.js 20 officially reached its End-of-Life (EOL) on April 30, 2026. It no longer receives official security updates, bug fixes, or critical patches. To ensure project security and maintain compatibility with modern deployment platforms, we need to audit the repository and upgrade our Node.js runtime support.

Todo List

• Audit the codebase and dependencies for compatibility with newer Node.js versions.
• Update the engines field in package.json to target the latest active LTS version.
• Update Node.js versions in CI/CD workflows (e.g., GitHub Actions, GitLab CI).
• Update local development documentation (e.g., README.md, .nvmrc).
• Run the test suite using the new Node.js version to verify stability.