The Kustomize build was failing because overlay images referenced
registry.nxtgauge.com:5000 but base deployments now use ghcr.io.
Also removed namespace from replicas-patch.yaml (namespace already removed from all base deployments)
Adds Kustomize base+prod overlays for nxtgauge-frontend-solid,
nxtgauge-admin-solid, and nxtgauge-backend-rust (18 services).
ArgoCD Image Updater configured for auto-deploy on high-performance-latest tag.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>