Summary

Add support for building container images for the ppc64le (IBM POWER) architecture, extending the existing multiplatform support which currently includes amd64, arm64, and s390x.

Motivation

IBM POWER systems (ppc64le) are widely used in enterprise environments, particularly for:

• High-performance computing workloads
• Enterprise database deployments
• AI/ML inference on IBM Power10 systems

Adding ppc64le support enables MCP Gateway deployment on IBM POWER infrastructure alongside existing IBM Z (s390x) support.

Proposed Changes

1. GitHub Actions workflow (docker-multiplatform.yml):

   • Add ppc64le to the build matrix with QEMU emulation
   • Include ppc64le in the multiplatform manifest

2. Containerfiles (Containerfile, Containerfile.lite):

   • Extend the OpenSSL workaround for grpcio (ppc64le lacks BoringSSL support, same as s390x)

3. Makefile:

   • Update container-build-multi target to include ppc64le

4. Documentation:

   • Update MULTIPLATFORM.md with ppc64le details
   • Update deployment and architecture docs

Technical Notes

• ppc64le builds will use QEMU emulation on GitHub Actions (similar to s390x)
• Expected build time: ~30-45 minutes under emulation
• grpcio requires GRPC_PYTHON_BUILD_SYSTEM_OPENSSL=True on ppc64le (same as s390x)

Acceptance Criteria

• Container builds successfully for linux/ppc64le
• Multiplatform manifest includes ppc64le
• Documentation updated to reflect ppc64le support
• CI pipeline passes with ppc64le builds