Lohnt sich dein eigenes Semrush?

Build me a rank-and-health tracker for sites I own, covering the
self-collectable slice of Semrush. Requirements:

- A Node CLI on a nightly cron: better-sqlite3 for history, and a static HTML
  report regenerated each run.
- Track 20-50 chosen keywords through a SERP API (Serper or DataForSEO, key in
  .env); store position per keyword per day and draw movement sparklines in the
  report.
- Pull clicks, impressions, and average position per query from the Google
  Search Console API for my own properties (OAuth creds in .env).
- A technical crawl of my own site with crawlee: broken links, missing titles
  and descriptions, redirect chains, slow pages, as a table in the report.
- Email the report weekly via Resend (key in .env), but only when something
  moved: a position swing over 3 places or new 404s.
- No accounts, no telemetry; all history lives in one SQLite file.
- Out of scope: competitor keyword gaps, backlink databases, and traffic
  estimates for sites I do not own. Do not scrape or estimate third-party data.
- README: the cheapest SERP API tier for daily checks, the GSC OAuth steps, and
  a note that Semrush's moat is years of crawled keyword, backlink, and SERP
  data no solo build can collect; this tracks only what I own.