This PR implements NIP-42 authentication support in the context of NIP-70 protected events, continuing the work originally started by @fiatjaf in #137.

Changes

NIP-42 Implementation (original work by @fiatjaf)

• Implements NIP-42 AUTH message handling
• Adds authentication support for NIP-70 protected events
• [Include any specific implementation details from the actual code changes if you know them]

CI/Build Fixes

• Updated GitHub Actions workflows to v4 (resolves build failures in original PR)
• Added build-essential package to ubuntu.yml workflow dependencies
• Updated Docker build actions (docker/login-action, docker/setup-qemu-action, docker/setup-buildx-action) to v3
• All CI checks now passing for both amd64 and arm64 platforms

Background

PR #137 introduced NIP-42 AUTH support but had CI failures that prevented merging. The workflow files needed updates to newer action versions and missing build dependencies.

Credit

Original NIP-42 implementation: @fiatjaf (#137)
CI fixes: @zk-bits

Related Issues

• Closes Implement nip 42 client authentication #47 (if this fully implements NIP-42 client authentication)
• Supersedes implement NIP-42 AUTH support in the context of NIP-70 protected events #137

Testing

• ✅ Ubuntu build successful
• ✅ Multi-platform Docker builds (linux/amd64, linux/arm64) successful
• ✅ All CI checks passing