The canonical Gitea runner is Linux-only, and this package hard-depends on
duckdb and httr2 -- both compiled, both with real platform variance --
while having never been checked on Windows or macOS. A large share of the
audience is on Windows.
Inert here: Gitea reads .gitea/workflows, GitHub reads .github/workflows,
so both configs coexist and the Gitea CI stays authoritative for deploys.
This goes live the moment the mirror repo exists (#44).
The matrix needs no credentials -- setup.R points at the bundled fixture --
which is why that fixture must never be .Rbuildignore'd.
