feat: wire @x-ocaml.requires through to worker init
- Add --copy-file flag to jtw opam/opam-all for including x-ocaml.js
and other assets in universe output
- Pass findlib_requires and findlib_index from meta tags through to
the JTW worker init, so @x-ocaml.requires packages are loaded
during setup
- x_ocaml.ml reads <meta name="x-ocaml-packages"> and
<meta name="x-ocaml-universe"> before creating the backend
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>