Add CI workflow for Docker image build and push

This workflow automates building and pushing Docker images for the backend and frontend to the Gitea registry. It triggers on `main` branch pushes, tag pushes, or manual dispatch and supports version tagging based on Git references.

.gitea/workflows/docker-build.yml

@@ -0,0 +1,73 @@
+name: Build and Push Docker Images
+
+on:
+  push:
+    branches: [ main ]
+    tags: [ 'v*' ]
+  workflow_dispatch:
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Gitea Registry
+        uses: docker/login-action@v3
+        with:
+          registry: gitea.pragmazest.com
+          username: ${{ secrets.DOCKER_REGISTRY_USERNAME }}
+          password: ${{ secrets.DOCKER_REGISTRY_ACCESS_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        run: |
+          if [[ $GITHUB_REF == refs/tags/* ]]; then
+            VERSION=${GITHUB_REF#refs/tags/v}
+          else
+            VERSION=latest
+          fi
+          echo "version=${VERSION}" >> $GITHUB_OUTPUT
+          echo "date=$(date -u +'%Y-%m-%dT%H:%M:%SZ')" >> $GITHUB_OUTPUT
+
+      # Build and push backend image
+      - name: Build and push backend
+        uses: docker/build-push-action@v5
+        with:
+          context: ./backend
+          file: ./backend/Dockerfile
+          push: true
+          target: production
+          tags: |
+            gitea.pragmazest.com/${{ github.repository }}/backend:${{ steps.meta.outputs.version }}
+            gitea.pragmazest.com/${{ github.repository }}/backend:latest
+          labels: |
+            org.opencontainers.image.created=${{ steps.meta.outputs.date }}
+            org.opencontainers.image.version=${{ steps.meta.outputs.version }}
+            org.opencontainers.image.revision=${{ github.sha }}
+
+      # Build and push frontend image
+      - name: Build and push frontend
+        uses: docker/build-push-action@v5
+        with:
+          context: ./frontend
+          file: ./frontend/Dockerfile
+          push: true
+          target: runner
+          tags: |
+            gitea.pragmazest.com/${{ github.repository }}/frontend:${{ steps.meta.outputs.version }}
+            gitea.pragmazest.com/${{ github.repository }}/frontend:latest
+          labels: |
+            org.opencontainers.image.created=${{ steps.meta.outputs.date }}
+            org.opencontainers.image.version=${{ steps.meta.outputs.version }}
+            org.opencontainers.image.revision=${{ github.sha }}
+
+      - name: Image digests
+        run: |
+          echo "Backend image: gitea.pragmazest.com/${{ github.repository }}/backend:${{ steps.meta.outputs.version }}"
+          echo "Frontend image: gitea.pragmazest.com/${{ github.repository }}/frontend:${{ steps.meta.outputs.version }}"