feat: Add CI/CD workflow and standalone admin documentation

- Add GitHub Actions workflow to build and push Docker image to ghcr.io
- Create comprehensive standalone admin usage guide
- Add .env.example for pgpool-admin configuration
- Update README with reference to standalone guide
- Use shorter image name: pgpool-dashboard

The workflow will automatically build multi-arch images (amd64/arm64) and
push to GitHub Container Registry on commits to main branch.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: omar-haris

.github/workflows/docker-build.yml

@@ -0,0 +1,79 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - 'pgpool-admin/**'
+      - '.github/workflows/docker-build.yml'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'pgpool-admin/**'
+      - '.github/workflows/docker-build.yml'
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository_owner }}/pgpool-dashboard
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Log in to the Container registry
+      if: github.event_name != 'pull_request'
+      uses: docker/login-action@v3
+      with:
+        registry: ${{ env.REGISTRY }}
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Extract metadata
+      id: meta
+      uses: docker/metadata-action@v5
+      with:
+        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+        tags: |
+          type=ref,event=branch
+          type=ref,event=pr
+          type=semver,pattern={{version}}
+          type=semver,pattern={{major}}.{{minor}}
+          type=raw,value=latest,enable={{is_default_branch}}
+          type=sha,prefix={{branch}}-
+
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v5
+      with:
+        context: ./pgpool-admin
+        push: ${{ github.event_name != 'pull_request' }}
+        tags: ${{ steps.meta.outputs.tags }}
+        labels: ${{ steps.meta.outputs.labels }}
+        cache-from: type=gha
+        cache-to: type=gha,mode=max
+        platforms: linux/amd64,linux/arm64
+
+    - name: Generate SBOM
+      if: github.event_name != 'pull_request'
+      uses: anchore/sbom-action@v0
+      with:
+        image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+        format: spdx-json
+        output-file: sbom.spdx.json
+
+    - name: Upload SBOM
+      if: github.event_name != 'pull_request'
+      uses: actions/upload-artifact@v4
+      with:
+        name: sbom
+        path: sbom.spdx.json

README.md

@@ -31,6 +31,8 @@ A PostgreSQL cluster setup with master-replica replication, PgPool-II load balan
 
 ## Quick Start
 
+> **💡 Using PgPool Admin Only?** See [Standalone Admin Guide](docs/STANDALONE_ADMIN.md) for monitoring your existing PostgreSQL/PgPool infrastructure.
+
 ### Prerequisites
 
 - Docker and Docker Compose v2.0+