Lohnt sich dein eigenes Orshot?

Build me a local templated image and PDF render service to replace an image generation API. Requirements:

- Node 22 with Express in a single server.js, plus Playwright driving Chromium.
  No build step, no framework, no database.
- A template is a folder at templates/<name>/ holding index.html with Handlebars
  placeholders, style.css, and meta.json with width, height, and defaults.
- Ship 3 starters: an OG card at 1200x630, an Instagram square at 1080x1080, and
  a one page invoice that renders to PDF.
- POST /render {template, modifications, format} returns PNG, JPEG, or PDF.
  Fill the template, set the viewport from meta.json, screenshot the page.
  PDFs go through page.pdf() instead.
- GET /render/<template>.png?headline=...&image=... does the same thing from
  query params so the URL can be dropped straight into an img tag.
- POST /batch accepts a CSV or a JSON array, renders every row into out/ with a
  concurrency of 4, and returns a manifest of paths.
- A brand.json with 4 colors and 2 local font files, injected into every template
  as CSS custom properties so a rebrand is one file edit.
- Keep one browser instance warm and reuse pages. Launching Chromium per request
  is the thing that makes the naive version unusable.
- Cache by a hash of template plus modifications into .cache/ and serve hits from
  disk before touching the browser.
- Fonts load from ./fonts via @font-face with file:// URLs, and the renderer waits
  on document.fonts.ready so text never screenshots mid swap.
- Out of scope: a visual editor, video, social publishing, and multi tenant auth.
  I write templates in HTML by hand and that is the trade I am making.
- README: how to add a template, how fonts resolve, and the Docker line that
  installs the Chromium system dependencies.