Use Artifacts system for meshes

There are a lot of failing CI runs caused by rate limit errors (HTTP/2 429) introduced recently, see https://github.blog/changelog/2025-05-08-updated-rate-limits-for-unauthenticated-requests/ and https://github.com/orgs/community/discussions/157887

We should likely switch to the Artifacts system of Julia (https://pkgdocs.julialang.org/v1.10/artifacts/) using caching to fix these issues.

Read Julia's Artifacts documentation and the linked GitHub rate-limit discussion first. Locate the CI workflow and current mesh-fetching or caching setup, then verify that meshes use Julia Artifacts and that CI runs no longer fail with HTTP/2 429 rate-limit errors.

Written by the indexing model from the issue text.