ci: publish MCP server images with SBOM attestations (#3437)

* ci: attach provenance and SBOM attestations to the published MCP server image

* ci: restore trailing newline at end of file

Author: kobihikri

.github/workflows/publish-mcp-server.yml

@@ -129,6 +129,8 @@ jobs:
         with:
           context: examples/mcp_server
           push: true
+          provenance: mode=max
+          sbom: true
           tags: |
             ${{ env.IMAGE_NAME }}:${{ steps.metadata.outputs.version }}
             ${{ env.IMAGE_NAME }}:latest