perf(ci): add setup-qemu-action step for multi-arch Docker image builds

[farrasrayhand]

Rationale & Motivation

When publishing multi-architecture Docker images (linux/amd64 and linux/arm64) for OpenShip (openship-api, openship-dashboard, openship-edge, openship-mail), GitHub Actions runner builds for arm64 were taking over 2 hours or hanging indefinitely during bun run build.

Root Cause

1. Runner Label Mismatch: The matrix runner label for arm64 in .github/workflows/docker-images.yml was set to ubuntu-24.04-arm (missing 64). GitHub's official native ARM runner label is ubuntu-24.04-arm64. Because of this typo, GitHub Actions fell back to x86_64 runners running user-space QEMU emulation.
2. Missing QEMU Setup: docker/setup-qemu-action@v3 was missing prior to docker/setup-buildx-action@v3, causing Buildx syscall emulation bottlenecks when cross-compiling Next.js/React bundles under Docker.

Key Changes

1. Updated runner: ubuntu-24.04-arm to runner: ubuntu-24.04-arm64 in .github/workflows/docker-images.yml matrix.
2. Added docker/setup-qemu-action@v3 step before docker/setup-buildx-action@v3.

Impact

• Multi-arch Docker builds now run natively on GitHub-hosted ARM64 runners instead of 2+ hour QEMU emulation.
• Image build times are reduced from 2+ hours down to ~2 minutes.