Node.js Build & KeyAuth Integration

I need the current Node.js project taken from my repo to compile cleanly on a fresh machine and then be extended with KeyAuth-based API-Key login. Right now the code only offers a simple basic-auth flow; I want that replaced (or wrapped, if easier) so users authenticate with a licence key handled through KeyAuth’s API.

Scope
• Set up the build from scratch, resolving all npm/yarn or webpack issues until a reproducible production bundle is generated.
• Wire KeyAuth into the project: when a user submits their key, the app should validate it via the KeyAuth endpoint and, on success, create the local session exactly where the old basic auth did. No registration or granular resource gating is required—just the login flow.
• Update env example variables, README and any middleware so another developer can run `npm install && npm start` and get identical results.
• Hand back the updated source plus the compiled output.

Acceptance
The app must start without errors, reach KeyAuth for validation, and allow entry only with a valid licence key; invalid keys must be rejected with the correct error response.

Please keep everything in plain JavaScript (Node.js LTS) and avoid introducing extra frameworks unless we agree beforehand.