ci: split frontend and backend into separate jobs to fix image tag mix-up

Both builds in the same job shared the same docker buildx instance,
causing the backend image to be incorrectly tagged with the frontend image.
Separate jobs get isolated buildx instances and separate build caches.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -23,7 +23,7 @@ env:
   BACKEND_IMAGE_NAME: valknar/sexy-backend
 
 jobs:
-  build-and-push:
+  build-frontend:
     runs-on: ubuntu-latest
 
     steps:
@@ -48,23 +48,17 @@ jobs:
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
-            # Tag as 'latest' for main branch
             type=raw,value=latest,enable={{is_default_branch}}
-            # Tag with branch name
             type=ref,event=branch
-            # Tag with PR number
             type=ref,event=pr
-            # Tag with git tag (semver)
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
             type=semver,pattern={{major}}
-            # Tag with commit SHA
             type=sha,prefix={{branch}}-
-            # Custom tag from workflow_dispatch
             type=raw,value=${{ gitea.event.inputs.tag }},enable=${{ gitea.event_name == 'workflow_dispatch' }}
           labels: |
             org.opencontainers.image.title=sexy.pivoine.art
-            org.opencontainers.image.description=Adult content platform with SvelteKit, Directus, and hardware integration
+            org.opencontainers.image.description=Adult content platform frontend (SvelteKit)
             org.opencontainers.image.vendor=valknar
             org.opencontainers.image.source=https://dev.pivoine.art/${{ gitea.repository }}
 
@@ -83,6 +77,35 @@ jobs:
             NODE_ENV=production
             CI=true
 
+      - name: Generate image digest
+        if: gitea.event_name != 'pull_request'
+        run: |
+          echo "### Frontend Image Published :rocket:" >> $GITEA_STEP_SUMMARY
+          echo "" >> $GITEA_STEP_SUMMARY
+          echo "**Registry:** \`${{ env.REGISTRY }}\`" >> $GITEA_STEP_SUMMARY
+          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
+          echo "${{ steps.meta.outputs.tags }}" >> $GITEA_STEP_SUMMARY
+          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
+
+  build-backend:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+        with:
+          platforms: linux/amd64
+
+      - name: Log in to Gitea Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ gitea.actor }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
       - name: Extract metadata for backend image
         id: meta-backend
         uses: docker/metadata-action@v5
@@ -121,39 +144,9 @@ jobs:
       - name: Generate image digest
         if: gitea.event_name != 'pull_request'
         run: |
-          echo "### Docker Images Published :rocket:" >> $GITEA_STEP_SUMMARY
+          echo "### Backend Image Published :rocket:" >> $GITEA_STEP_SUMMARY
           echo "" >> $GITEA_STEP_SUMMARY
           echo "**Registry:** \`${{ env.REGISTRY }}\`" >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "**Frontend (\`${{ env.IMAGE_NAME }}\`):**" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "${{ steps.meta.outputs.tags }}" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "**Backend (\`${{ env.BACKEND_IMAGE_NAME }}\`):**" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "${{ steps.meta-backend.outputs.tags }}" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "**Pull commands:**" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`bash" >> $GITEA_STEP_SUMMARY
-          echo "docker pull ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest" >> $GITEA_STEP_SUMMARY
-          echo "docker pull ${{ env.REGISTRY }}/${{ env.BACKEND_IMAGE_NAME }}:latest" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-
-      - name: PR Comment - Images built but not pushed
-        if: gitea.event_name == 'pull_request'
-        run: |
-          echo "### Docker Images Built Successfully :white_check_mark:" >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "Images were built successfully but **not pushed** (PR builds are not published)." >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "**Frontend would be tagged as:**" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "${{ steps.meta.outputs.tags }}" >> $GITEA_STEP_SUMMARY
-          echo "\`\`\`" >> $GITEA_STEP_SUMMARY
-          echo "" >> $GITEA_STEP_SUMMARY
-          echo "**Backend would be tagged as:**" >> $GITEA_STEP_SUMMARY
           echo "\`\`\`" >> $GITEA_STEP_SUMMARY
           echo "${{ steps.meta-backend.outputs.tags }}" >> $GITEA_STEP_SUMMARY
           echo "\`\`\`" >> $GITEA_STEP_SUMMARY