Teachable

Build me a single-course sales site to replace Teachable, for one course of mine. Requirements: - Node + Express + better-sqlite3 on my VPS behind Caddy. Course content is Markdown in content/: one folder per module, one file per lesson, front matter points at an optional video file. - Public landing page: course outline, price, and a Buy button that goes to Stripe Checkout (keys in .env). The Stripe webhook marks the buyer's email as enrolled. - Student login by magic link: enter email, receive a signed login link via SMTP creds in .env. No passwords, no OAuth. - Lesson pages are gated by enrollment; videos are MP4s served through the app with short-lived signed URLs so direct links expire. - Progress: a mark-complete button per lesson and a progress bar per module, stored per student in SQLite. - Receipts come from Stripe; do not build invoicing or tax logic (turn on Stripe Tax if needed). - Out of scope: multiple courses, affiliates, certificates, upsells, coupons, and mobile apps. This sells and delivers one course. - README: Stripe webhook setup, Caddy snippet, where videos live on disk, and an honest note that a VPS handles a small audience fine but a big launch needs real video hosting like Bunny.net.