Add ARM64 support for Raspberry Pi Docker builds

- Add QEMU emulation step for cross-platform builds
- Remove redundant docker-publish.yml workflow
- build.yml now handles all CI/CD including multi-arch images

Author: brdweb

.github/workflows/build.yml

@@ -64,6 +64,9 @@ jobs:
       - name: Checkout repository
         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