Kann Invoice Ninja weg?

Build me a small invoicing app to replace hosted Invoice Ninja. Requirements:

- Note in the README that Invoice Ninja itself is open source and self-hostable;
  this build is the lighter option for someone who needs invoices, not a platform.
- Node + Express + better-sqlite3, admin UI on localhost:4840, server-rendered pages.
- Clients (name, email, address, currency, default rate) and invoices with line items
  (description, qty, unit price, tax %), auto-numbered INV-2026-001 style.
- Generate a clean PDF per invoice with puppeteer from an HTML template: my logo,
  payment terms, and bank details read from a config file.
- Email the PDF to the client via SMTP (creds in .env); track draft/sent/paid status
  and show a dashboard of unpaid invoices with days outstanding.
- Optional Stripe payment link per invoice (key in .env), included in the PDF and
  the email. I mark invoices paid by hand when money lands.
- Nightly backup: copy the SQLite file to backups/YYYY-MM-DD.db, keep 30.
- Binds to localhost, no client portal, no accounts, no telemetry.
- Out of scope: quotes, expenses, multi-user, and automatic payment reconciliation.
- README: .env keys, how to edit the invoice template, and the numbering rule.