fix(release): build RPM directly on ubuntu runner without Docker

Docker volume mounts in Gitea CI don't expose the runner workspace
correctly, leaving /build empty inside the container. Since the pgtidy
binary is statically linked Go with no shared-lib deps, rpmbuild runs
fine on ubuntu-latest with the rpm package. Drops Docker entirely from
the RPM job.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -171,30 +171,21 @@ jobs:
           set -euo pipefail
           VERSION="${{ github.event.inputs.tag || github.ref_name }}"
           PKGVER="${VERSION#v}"
-          GO_ROOT="$(go env GOROOT)"
+
+          sudo apt-get install -y rpm
 
           git archive --format=tar.gz --prefix=pgtidy-${PKGVER}/ HEAD \
             > pgtidy-${PKGVER}.tar.gz
 
           sed -i "s/^Version:.*/Version:        ${PKGVER}/" linux/centos/pgtidy.spec
 
+          mkdir -p ~/rpmbuild/{BUILD,BUILDROOT,RPMS,SOURCES,SPECS,SRPMS}
+          cp pgtidy-${PKGVER}.tar.gz ~/rpmbuild/SOURCES/
+          cp linux/centos/pgtidy.spec ~/rpmbuild/SPECS/
+          rpmbuild --nodeps -ba ~/rpmbuild/SPECS/pgtidy.spec
+
           mkdir -p rpm-out
-          docker run --rm \
+          find ~/rpmbuild/RPMS/ -name '*.rpm' -exec cp {} rpm-out/ \;
-            -v "$(pwd):/build" \
-            -v "${GO_ROOT}:/usr/local/go:ro" \
-            -e PKGVER="${PKGVER}" \
-            -w /build \
-            rockylinux:9 \
-            bash -lc "
-              set -euo pipefail
-              export PATH=\$PATH:/usr/local/go/bin &&
-              dnf install -y rpm-build git &&
-              mkdir -p ~/rpmbuild/{BUILD,BUILDROOT,RPMS,SOURCES,SPECS,SRPMS} &&
-              cp pgtidy-${PKGVER}.tar.gz ~/rpmbuild/SOURCES/ &&
-              cp linux/centos/pgtidy.spec ~/rpmbuild/SPECS/ &&
-              rpmbuild --nodeps -ba ~/rpmbuild/SPECS/pgtidy.spec &&
-              find ~/rpmbuild/RPMS/ -name '*.rpm' -exec cp {} /build/rpm-out/ \;
-            "
 
       - name: Upload to release
         run: |