Add Forgejo Actions CI/CD workflow

Create automated build and deploy workflow that:
- Triggers on push to main branch
- Builds Docker image with timestamped tag
- Pushes to registry.basicstack.de (10.106.73.119:5000)
- Updates k8s/20-deployment.yaml with new image tag
- Commits manifest update for Argo CD to sync

Part of DEV-334 CI/CD workflow implementation.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.forgejo/workflows/build-and-deploy.yaml

@@ -0,0 +1,71 @@
+name: Build and Deploy
+
+on:
+  push:
+    branches:
+      - main
+
+env:
+  REGISTRY: 10.106.73.119:5000
+  IMAGE_NAME: basicstack-web
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Docker image tags
+        id: meta
+        run: |
+          echo "TAG=$(date +%Y%m%d-%H%M%S)-${GITHUB_SHA:0:7}" >> $GITHUB_OUTPUT
+          echo "FULL_IMAGE=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:$(date +%Y%m%d-%H%M%S)-${GITHUB_SHA:0:7}" >> $GITHUB_OUTPUT
+          echo "LATEST_IMAGE=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest" >> $GITHUB_OUTPUT
+
+      - name: Build Docker image
+        run: |
+          docker build \
+            -t ${{ steps.meta.outputs.FULL_IMAGE }} \
+            -t ${{ steps.meta.outputs.LATEST_IMAGE }} \
+            -f Dockerfile .
+
+      - name: Log in to container registry
+        run: |
+          echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login ${{ env.REGISTRY }} \
+            -u paperclip --password-stdin
+
+      - name: Push Docker image
+        run: |
+          docker push ${{ steps.meta.outputs.FULL_IMAGE }}
+          docker push ${{ steps.meta.outputs.LATEST_IMAGE }}
+
+      - name: Update deployment manifest
+        run: |
+          cd k8s
+          sed -i "s|image:.*basicstack-web.*|image: ${{ steps.meta.outputs.FULL_IMAGE }}|" 20-deployment.yaml
+          cat 20-deployment.yaml | grep -A2 "image:"
+
+      - name: Commit and push manifest update
+        run: |
+          git config user.name "Forgejo Actions"
+          git config user.email "actions@forgejo.basicstack.de"
+          git add k8s/20-deployment.yaml
+          git diff --cached --exit-code || (
+            git commit -m "chore: update deployment image to ${{ steps.meta.outputs.TAG }}
+
+          Automated image update from CI/CD workflow.
+
+          Co-Authored-By: Paperclip <noreply@paperclip.ing>" &&
+            git push origin main
+          )
+
+      - name: Deployment summary
+        run: |
+          echo "## Deployment Complete" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "- **Image**: ${{ steps.meta.outputs.FULL_IMAGE }}" >> $GITHUB_STEP_SUMMARY
+          echo "- **Registry**: ${{ env.REGISTRY }}" >> $GITHUB_STEP_SUMMARY
+          echo "- **Manifest updated**: k8s/20-deployment.yaml" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "Argo CD will automatically sync the deployment to the cluster." >> $GITHUB_STEP_SUMMARY