ci: attach .deb and .rpm packages to releases and nightlies

Built by nfpm from the static musl binaries, with the man page and the
bash, zsh and fish completions. The names carry no version, so
releases/latest/download/soulseek-rs-amd64.deb stays a working link; the
nightly pair replaces itself on the rolling prerelease.

.github/workflows/release.yml

@@ -200,6 +200,16 @@ jobs:
           ref: refs/tags/${{ needs.release.outputs.tag }}
           token: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Build and upload .deb and .rpm
+        if: endsWith(matrix.target, '-musl') && hashFiles('scripts/package-linux.sh') != ''
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ needs.release.outputs.tag }}
+          TARGET: ${{ matrix.target }}
+        run: |
+          sh scripts/package-linux.sh "target/$TARGET/release/soulseek-rs" "${TAG#v}" "$TARGET" dist
+          gh release upload "$TAG" dist/* --clobber
+
   # The tap regenerates its formula from whatever `gh release view` calls latest,
   # so it only needs a nudge once every archive and .sha256 is on the release —
   # hence `needs: binaries` rather than firing alongside it. The tap also polls