Add multiarch Docker support and GHCR publishing

- Implement multiarch Dockerfile supporting linux/amd64 and linux/arm64
- Optimize Dockerfile with better layer caching and reduced image size
- Update CI/CD pipeline to use Docker Buildx for multiarch builds
- Add GitHub Container Registry (GHCR) as second publishing target
- Configure automatic tagging (latest, branch name, commit SHA)
- Add QEMU emulation support for cross-platform builds
- Enable GitHub Actions layer caching for faster builds
- Completely revamp README with comprehensive documentation
- Add professional badges (build status, Docker Hub, GHCR, license, Python)
- Include detailed setup instructions for Docker Hub and GHCR
- Add Docker Compose example and configuration table
- Document multiarch build process and state persistence

.github/workflows/masto-rss.yml

@@ -5,16 +5,55 @@ on:
    branches: [ main ]
   pull_request:
     branches: [ main ]
-      
+
 jobs:
   build:
-
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
 
     steps:
-    - uses: actions/checkout@v1
-    - name: Build & Push Image
-      run: |
-        echo "${{ secrets.DH_PASSWORD }}" | docker login -u "amitserper" --password-stdin
-        docker build -t amitserper/masto-rss .
-        docker push amitserper/masto-rss
+    - uses: actions/checkout@v4
+
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v3
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Login to Docker Hub
+      uses: docker/login-action@v3
+      with:
+        username: amitserper
+        password: ${{ secrets.DH_PASSWORD }}
+
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v3
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Extract metadata
+      id: meta
+      uses: docker/metadata-action@v5
+      with:
+        images: |
+          amitserper/masto-rss
+          ghcr.io/aserper/masto-rss
+        tags: |
+          type=ref,event=branch
+          type=sha,prefix={{branch}}-
+          type=raw,value=latest,enable={{is_default_branch}}
+
+    - name: Build and push multiarch image
+      uses: docker/build-push-action@v5
+      with:
+        context: .
+        platforms: linux/amd64,linux/arm64
+        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