Add harness app: agent orchestrator with cluster deployment

- Next.js app for orchestrating coding agent benchmarks (Claude Code, Codex, OpenCode)
- Dockerfile installs git, gh CLI, and agent CLIs for headless execution
- K8s deployment with workspace volume, sealed credentials for Claude + OpenCode
- Traefik IngressRoute at harness.coreworlds.io with internal-only middleware + TLS
- CI pipeline path filter for harness builds
- Fix OpenCode runtime flags (subcommand-based headless mode)

apps/harness/k8s/overlays/preview/kustomization.yaml

@@ -0,0 +1,15 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - ../../base
+patches:
+  - target:
+      kind: Deployment
+      name: harness
+    patch: |
+      apiVersion: apps/v1
+      kind: Deployment
+      metadata:
+        name: harness
+      spec:
+        replicas: 1

apps/harness/k8s/overlays/production/kustomization.yaml

@@ -0,0 +1,19 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- ../../base
+patches:
+- patch: |
+    apiVersion: apps/v1
+    kind: Deployment
+    metadata:
+      name: harness
+    spec:
+      replicas: 1
+  target:
+    kind: Deployment
+    name: harness
+images:
+- name: ghcr.io/lazorgurl/homelab-harness
+  newName: ghcr.io/lazorgurl/homelab-harness
+  newTag: latest