Lohnt sich dein eigenes beehiiv?

Build me a personal newsletter system to replace beehiiv. Requirements:

- Node + Express + better-sqlite3. Posts are Markdown files in posts/;
  subscribers live in SQLite: email, token, subscribed_at, unsubscribed_at.
- A localhost admin page: write and preview a post (marked, rendered inside
  a tested single-column email HTML template), see subscriber count, send.
- Sending via Resend or plain SMTP, creds in .env. Every email carries a
  one-click unsubscribe link (token in the URL) and a List-Unsubscribe
  header; that is a legal requirement, never skip it.
- Log each send per subscriber as sent or failed so an interrupted batch
  resumes without double-sending anyone.
- Public surface, deployable as one small server: a subscribe form with a
  double-opt-in confirmation email, and a web archive of past posts at
  /archive.
- CSV import and export of the subscriber list.
- Out of scope: open/click analytics, referral programs, and paid
  subscriptions; beehiiv's growth network is the actual product.
- README: .env keys, the ESP's SPF/DKIM DNS records, and a blunt warning to
  warm up a new sending domain slowly or everything lands in spam;
  deliverability is most of what the fee buys.