fix: use valid artifact name for SBOM upload

The default artifact name includes sha256 hash with colons which are
invalid for GitHub artifact names. Use simple image name instead.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: samuelho-dev

.github/workflows/docker-build-push.yml

@@ -200,6 +200,7 @@ jobs:
           image: ${{ inputs.registry }}/${{ github.repository_owner }}/${{ inputs.image }}@${{ steps.build.outputs.digest }}
           format: 'spdx-json'
           output-file: 'sbom.spdx.json'
+          artifact-name: ${{ inputs.image }}-sbom.spdx.json
           upload-artifact: true
           upload-release-assets: false