v1.4.0 — catalog_info options, Rosa3D catalogue example, TigerSystem

Added

• Showcase site (site/), published on GitHub Pages at
  https://tigertag-project.github.io/TigerTag-SDK-Python/ by .github/workflows/pages.yml,
  in eleven languages, with a "Get started with Python" button at the top of the README.
  Not part of the package.

Changed

• The catalogue example in the README, the docstrings and the playground is now product
  2673739332, Rosa3D PLA Rainbow - Fire 1000 g: 3527039449 (Elegoo Rapid TPU 95A - Black)
  left the catalogue. The tests that read the bundled copy use it too.
• The copyright and trademark holder is named TigerSystem (formerly TigerTag Corp) in the
  licence, the source headers and the README.
• CI tests Python 3.8 on ubuntu-22.04, since ubuntu-latest no longer ships it.
• catalog_info() now takes the same options as the JS SDK's catalogInfo(): data_dir
  (alias of cache_dir) and offline (accepted for symmetry with load_catalog(); the
  function only reads local files, so it never uses the network).