The TypeScript and Rust Quickstarts read the image from ../../docs/static,
the layout before the documentation moved into this repository. The file is
docs/web/static/assets/images/quickstart/sir-lancelot.jpg, so the TypeScript
test failed with ENOENT and the Rust example panicked at the read. Both now
resolve the image from the example's own directory (__dirname and
CARGO_MANIFEST_DIR), and the two Quickstart exports are regenerated with
docs/web-tests/mdx_snippets_gen.py.