refactor: restructure rpm repo path to distro/version/arch layout

Move from /var/www/rpm/mistralrs/fedora-43/x86_64/ to
/var/www/rpm/fedora/43/x86_64/ so the repo can host packages
from multiple projects under a conventional hierarchy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/poll-upstream.yml

@@ -25,7 +25,7 @@ jobs:
           # Query our own dnf repo. If the version is there, we've already built it.
           # Strip leading 'v' because RPM versions don't use it.
           version="${UPSTREAM_TAG#v}"
-          if curl -sSfI "https://rpm.lair.cafe/mistralrs/fedora-43/x86_64/mistralrs-server-cuda13-fa-${version}-1.fc43.x86_64.rpm" | grep -q '^HTTP.*200'; then
+          if curl -sSfI "https://rpm.lair.cafe/fedora/43/x86_64/mistralrs-server-cuda13-fa-${version}-1.fc43.x86_64.rpm" | grep -q '^HTTP.*200'; then
             echo "already_built=true" >> "$GITHUB_OUTPUT"
           else
             echo "already_built=false" >> "$GITHUB_OUTPUT"