Healthcheck Node concepts

nodeRuntimeAdapter() supplies process identity, uptime, memory, CPU, and shutdown hooks.

Container detection reads cgroup v2 and v1, then falls back to constrained-process and OS values. A fractional CPU quota such as 0.5 is preserved. Low-confidence detection makes the default container check degraded, not unhealthy.

processMetricsCollector() and containerMetricsCollector() add monitoring series. tcpCheck() and dnsCheck() are readiness checks by default. They are probes, not HTTP route handlers.