fix(ci): make Docker Hub login optional in release workflow (fork-friendly)

Author: josecarlospeer-cloud

.github/workflows/release.yaml

@@ -20,6 +20,7 @@ jobs:
     env:
       VERSION: ${{ matrix.version }}
       ARCHS: ${{ matrix.arch }}
+      REGISTRY_USERNAME: ${{ secrets.REGISTRY_USERNAME }}
     name: release-${{ matrix.version }}
     runs-on: ubuntu-latest
     steps:
@@ -32,8 +33,14 @@ jobs:
       id: buildx
       uses: docker/setup-buildx-action@v3
     - name: Login to Docker Hub
+      if: env.REGISTRY_USERNAME != ''
       uses: docker/login-action@v3
       with:
         username: ${{ secrets.REGISTRY_USERNAME }}
         password: ${{ secrets.REGISTRY_PASSWORD }}
-    - run: make release
+    - name: Build and push
+      if: env.REGISTRY_USERNAME != ''
+      run: make release
+    - name: Build only (no push credentials)
+      if: env.REGISTRY_USERNAME == ''
+      run: make build