Chore: Migrate project environment from Node v16 to Node v22

Description

Currently, the EmbeddedChat project is running on Node.js 16.19.0. Node 16 reached its End-of-Life (EOL) in September 2023. As a result, maintaining the project on this version poses potential security risks, prevents the use of modern Node features (like the native fetch API and modern fs methods), and causes compatibility issues with newer tooling and dependencies. This issue tracks the work to migrate the project's recommended Node.js version to the active Long Term Support (LTS) release, Node v22.22.1.

Motivation

• Security & Support: Node 16 is no longer maintained. Node 22 provides active security updates.
• Modern Features: Node 18+ introduced a native global fetch and .mjs/.cjs recursive directory reading methods. The codebase is already using some of these methods in builds, so bumping the official Node version ensures stability and correct feature detection.
• Improved DX and Tooling Compatibility: Modern libraries and tools (like Vite and Rollup plugins) are increasingly dropping support for Node 16.

Start by locating the project’s Node.js version configuration and all tooling references to Node 16.19.0. Check the build and dependency tooling for Node 22.22.1 compatibility, then run the project’s existing checks to confirm the migration does not break builds or development workflows.