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/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "@homelab/harness",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev --port 3100",
+    "build": "next build",
+    "start": "next start",
+    "lint": "next lint",
+    "test": "echo \"no tests yet\""
+  },
+  "dependencies": {
+    "next": "^15.1.0",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "yaml": "^2.7.0"
+  },
+  "devDependencies": {
+    "@types/node": "^22.10.0",
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "typescript": "^5.7.0"
+  }
+}