Add new features and enhancements to CI workflows and backend.

Enhanced CI workflows by adding an Alpine-based smoke test for the backend with PostgreSQL 16. Updated the Docker build process to support dynamic base images and added provenance, SBOM, and labels to Docker builds. Extended branch compatibility checks and refined backend configurations for broader usage scenarios.

.github/workflows/docker-release.yml

@@ -16,6 +16,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: read
+      id-token: write
+      attestations: write
 
     env:
       # Optional repo variable. If unset, DOCKERHUB_USERNAME is used.
@@ -70,6 +72,13 @@ jobs:
           context: ./backend
           file: ./backend/Dockerfile
           push: true
+          provenance: mode=max
+          sbom: true
+          labels: |
+            org.opencontainers.image.title=NexaPG Backend
+            org.opencontainers.image.vendor=Nesterovic IT-Services e.U.
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
+            org.opencontainers.image.version=${{ steps.ver.outputs.clean }}
           tags: |
             ${{ steps.ns.outputs.value }}/nexapg-backend:${{ steps.ver.outputs.clean }}
             ${{ steps.ns.outputs.value }}/nexapg-backend:latest
@@ -82,8 +91,15 @@ jobs:
           context: ./frontend
           file: ./frontend/Dockerfile
           push: true
+          provenance: mode=max
+          sbom: true
           build-args: |
             VITE_API_URL=/api/v1
+          labels: |
+            org.opencontainers.image.title=NexaPG Frontend
+            org.opencontainers.image.vendor=Nesterovic IT-Services e.U.
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
+            org.opencontainers.image.version=${{ steps.ver.outputs.clean }}
           tags: |
             ${{ steps.ns.outputs.value }}/nexapg-frontend:${{ steps.ver.outputs.clean }}
             ${{ steps.ns.outputs.value }}/nexapg-frontend:latest