ci(demo-service): GitHub Actions workflow for ghcr.io build

- .github/workflows/build-demo-service.yml builds on push when home-apps/demo-service/**
- Pushes to ghcr.io/wahyd4/demo-manager with git SHA tag + :latest
- Updates k8s-manifest.yaml with new image tag
- ArgoCD picks up the new image on next sync

k8s-manifest changes:
- image: ghcr.io/wahyd4/demo-manager (was docker.io/library/demo-manager)
- imagePullPolicy: Always
- imagePullSecrets: github-image-pull-secret (auth for ghcr.io)

.github/workflows/build-demo-service.yml

@@ -0,0 +1,73 @@
+name: Build demo-service
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - 'home-apps/demo-service/**'
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  packages: write
+
+jobs:
+  build:
+    name: Build & update manifest
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to ghcr.io
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Compute image tag
+        id: tag
+        run: |
+          SHA="${{ github.sha }}"
+          SHORT_SHA="${SHA:0:7}"
+          TAG="git-${SHORT_SHA}"
+          echo "tag=${TAG}" >> "$GITHUB_OUTPUT"
+          echo "full_image=ghcr.io/${{ github.repository_owner }}/demo-manager:${TAG}" >> "$GITHUB_OUTPUT"
+
+      - name: Build & push image
+        uses: docker/build-push-action@v5
+        with:
+          context: home-apps/demo-service
+          file: home-apps/demo-service/Dockerfile
+          push: true
+          tags: |
+            ghcr.io/${{ github.repository_owner }}/demo-manager:${{ steps.tag.outputs.tag }}
+            ghcr.io/${{ github.repository_owner }}/demo-manager:latest
+          labels: |
+            org.opencontainers.image.revision=${{ github.sha }}
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}
+
+      - name: Update manifest with new image tag
+        run: |
+          IMAGE="${{ steps.tag.outputs.full_image }}"
+          echo "Updating manifest to: ${IMAGE}"
+          sed -i "s|image: docker.io/library/demo-manager:.*|image: ${IMAGE}|" home-apps/demo-service/k8s-manifest.yaml
+          sed -i "s|imagePullPolicy:.*|imagePullPolicy: Always|" home-apps/demo-service/k8s-manifest.yaml
+          # Show what changed
+          git diff home-apps/demo-service/k8s-manifest.yaml
+
+      - name: Commit & push manifest update
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add home-apps/demo-service/k8s-manifest.yaml
+          if git diff --cached --quiet; then
+            echo "No manifest changes to commit"
+            exit 0
+          fi
+          git commit -m "ci(demo-service): bump image to ${{ steps.tag.outputs.tag }}"
+          git push

home-apps/demo-service/k8s-manifest.yaml

@@ -108,8 +108,12 @@ spec:
               cpu: 200m
 
         - name: api
-          image: docker.io/library/demo-manager:latest
-          imagePullPolicy: IfNotPresent
+          # Image is updated automatically by .github/workflows/build-demo-service.yml
+          # on every push that changes home-apps/demo-service/**
+          image: ghcr.io/wahyd4/demo-manager:PLACEHOLDER
+          imagePullPolicy: Always
+          imagePullSecrets:
+            - name: github-image-pull-secret
           ports:
             - containerPort: 3000
               name: api