P3.2+P3.3+P3.4: NODA1 node-worker + NATS auth config + Prometheus counters

P3.2 — Multi-node deployment:
- Added node-worker service to docker-compose.node1.yml (NODE_ID=noda1)
- NCS NODA1 now has NODE_WORKER_URL for metrics collection
- Fixed NODE_ID consistency: router NODA1 uses 'noda1'
- NODA2 node-worker/NCS gets NCS_REPORT_URL for latency reporting

P3.3 — NATS accounts/auth (opt-in config):
- config/nats-server.conf with 3 accounts: SYS, FABRIC, APP
- Per-user topic permissions (router, ncs, node_worker)
- Leafnode listener :7422 with auth
- Not yet activated (requires credential provisioning)

P3.4 — Prometheus counters:
- Router /fabric_metrics: caps_refresh, caps_stale, model_select,
  offload_total, breaker_state, score_ms histogram
- Node Worker /prom_metrics: jobs_total, inflight gauge, latency_ms histogram
- NCS /prom_metrics: runtime_health, runtime_p50/p95, node_wait_ms
- All bound to 127.0.0.1 (not externally exposed)

Made-with: Cursor

services/node-capabilities/prom_metrics.py

@@ -0,0 +1,50 @@
+"""Prometheus metrics for NCS."""
+import logging
+
+logger = logging.getLogger("ncs_prom")
+
+try:
+    from prometheus_client import Gauge, CollectorRegistry, generate_latest
+    PROM_AVAILABLE = True
+    REGISTRY = CollectorRegistry()
+
+    runtime_health = Gauge(
+        "ncs_runtime_health", "Runtime health (1=ok, 0=down)",
+        ["runtime"], registry=REGISTRY,
+    )
+    runtime_p50 = Gauge(
+        "ncs_runtime_p50_ms", "Runtime p50 latency",
+        ["runtime"], registry=REGISTRY,
+    )
+    runtime_p95 = Gauge(
+        "ncs_runtime_p95_ms", "Runtime p95 latency",
+        ["runtime"], registry=REGISTRY,
+    )
+    node_wait = Gauge(
+        "ncs_node_wait_ms", "Estimated wait for node",
+        registry=REGISTRY,
+    )
+
+except ImportError:
+    PROM_AVAILABLE = False
+    REGISTRY = None
+
+
+def update_from_caps(caps: dict):
+    if not PROM_AVAILABLE:
+        return
+    nl = caps.get("node_load", {})
+    node_wait.set(nl.get("estimated_wait_ms", 0))
+    for rl in caps.get("runtime_load", []):
+        rt = rl.get("runtime", "?")
+        runtime_health.labels(runtime=rt).set(1 if rl.get("healthy") else 0)
+        if rl.get("p50_ms") is not None:
+            runtime_p50.labels(runtime=rt).set(rl["p50_ms"])
+        if rl.get("p95_ms") is not None:
+            runtime_p95.labels(runtime=rt).set(rl["p95_ms"])
+
+
+def get_metrics_text():
+    if PROM_AVAILABLE and REGISTRY:
+        return generate_latest(REGISTRY)
+    return None