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/next.config.js

@@ -0,0 +1,6 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  output: "standalone",
+};
+
+module.exports = nextConfig;