feat: OpenShift deployment with Red Hat MCP Gateway support

[jor2]

Summary

• Add /health endpoint checking GitHub API and Terraform Registry connectivity
• Add PORT envvar support for container platforms
• Add UBI9 multi-stage Dockerfile running as non-root on port 8080
• Add Kustomize manifests with base + MCP Gateway and standalone overlays
• Add MCPServerRegistration CRD for gateway tool discovery with tim_ prefix
• Add NetworkPolicy restricting ingress to gateway namespace
• Add GitHub Actions workflow for container image builds to GHCR
• Add unit and integration tests for health endpoint
• Update deployment docs with container and OpenShift instructions

Test plan

• Unit tests pass (61/61 including 4 new health endpoint tests)
• Kustomize manifests validated with kubectl kustomize for all overlays
• Deployed and verified on ROKS cluster: health endpoint, MCP init, tool discovery, search all functional