ci: conditionally assign latest tag to dev builds or releases

- Add latest tag to main branch only when no version tags exist
- Switch latest tag to version releases once they are available

Author: AWildLeon

.github/workflows/docker-image.yml

@@ -43,6 +43,16 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      # Check if any version tags exist
+      - name: Check for existing version tags
+        id: check-tags
+        run: |
+          if git tag --list 'v*.*' | grep -q .; then
+            echo "has_version_tags=true" >> $GITHUB_OUTPUT
+          else
+            echo "has_version_tags=false" >> $GITHUB_OUTPUT
+          fi
+
       # Extract metadata (tags, labels) for Docker
       # https://github.com/docker/metadata-action
       - name: Extract Docker metadata
@@ -52,7 +62,11 @@ jobs:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
             type=raw,value=testing-${{ github.ref_name }}
-            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' }}
+            type=raw,value=testing-main,enable=${{ github.ref == 'refs/heads/main' }}
+            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' && steps.check-tags.outputs.has_version_tags == 'false' }}
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
 
       # Build and push Docker image with Buildx (don't push on PR)
       # https://github.com/docker/build-push-action