Add Docker Hub image publishing to CI/CD

[Awaiswilll]

Description

Add a GitHub Actions workflow that builds and publishes a Docker image to Docker Hub on every release tag.

What Needs to Be Done

• Create Dockerfile for production
• Add GitHub Actions workflow for Docker build/push
• Configure Docker Hub credentials as GitHub secrets
• Tag images with version and latest
• Add multi-arch support (linux/amd64, linux/arm64)

Acceptance Criteria

• Docker image builds on release tag
• Image is pushed to Docker Hub
• Image runs with: docker run -d -p 49737:49737 dweb/dweb:latest
• Multi-arch images are available

Relevant Files

• .github/workflows/docker.yml — New workflow
• Dockerfile — New file
• packaging/wsl/Dockerfile — Can be adapted