chore: Update Docker documentation and optimize Dockerfile for caching

- Revised DOCKER.md to recommend building directly with `docker build` for improved compatibility on ARM devices and clarified the use of host network mode.
- Enhanced Dockerfile to utilize cache mounts for apt and pip installations, improving build efficiency and reducing redundant downloads.
- Updated GitHub Actions workflow to support multi-platform builds for both amd64 and arm64 architectures, ensuring broader compatibility.

.github/workflows/docker-build.yml

@@ -30,6 +30,8 @@ jobs:
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+        with:
+          platforms: linux/amd64,linux/arm64
 
       - name: Log in to Container Registry
         if: github.event_name != 'pull_request'
@@ -63,3 +65,5 @@ jobs:
           cache-from: type=gha
           cache-to: type=gha,mode=max
           platforms: linux/amd64,linux/arm64
+          # Build for both amd64 and arm64 architectures
+          # This enables the image to run on both x86_64 and ARM devices (Raspberry Pi, Orange Pi, etc.)