P2: Global multi-node model selection + NCS on NODA1

Architecture for 150+ nodes:
- global_capabilities_client.py: NATS scatter-gather discovery using
  wildcard subject node.*.capabilities.get — zero static node lists.
  New nodes auto-register by deploying NCS and subscribing to NATS.
  Dead nodes expire from cache after 3x TTL automatically.

Multi-node model_select.py:
- ModelSelection now includes node, local, via_nats fields
- select_best_model prefers local candidates, then remote
- Prefer list resolution: local first, remote second
- All logged per request: node, runtime, model, local/remote

NODA1 compose:
- Added node-capabilities service (NCS) to docker-compose.node1.yml
- NATS subscription: node.noda1.capabilities.get
- Router env: NODE_CAPABILITIES_URL + ENABLE_GLOBAL_CAPS_NATS=true

NODA2 compose:
- Router env: ENABLE_GLOBAL_CAPS_NATS=true

Router main.py:
- Startup: initializes global_capabilities_client (NATS connect + first
  discovery). Falls back to local-only capabilities_client if unavailable.
- /infer: uses get_global_capabilities() for cross-node model pool
- Offload support: send_offload_request(node_id, type, payload) via NATS

Verified on NODA2:
- Global caps: 1 node, 14 models (NODA1 not yet deployed)
- Sofiia: cloud_grok → grok-4-1-fast-reasoning (OK)
- Helion: NCS → qwen3:14b local (OK)
- When NODA1 deploys NCS, its models appear automatically via NATS discovery

Made-with: Cursor

docker-compose.node2-sofiia.yml

@@ -25,8 +25,9 @@ services:
       - XAI_API_KEY=${XAI_API_KEY}
       - GROK_API_KEY=${XAI_API_KEY}
       - DEEPSEEK_API_KEY=${DEEPSEEK_API_KEY:-}
-      # ── Node Capabilities ─────────────────────────────────────────────────
+      # ── Node Capabilities (multi-node model selection) ────────────────────
       - NODE_CAPABILITIES_URL=http://node-capabilities:8099/capabilities
+      - ENABLE_GLOBAL_CAPS_NATS=true
       # ── Persistence backends ──────────────────────────────────────────────
       - ALERT_BACKEND=postgres
       - ALERT_DATABASE_URL=${ALERT_DATABASE_URL:-${DATABASE_URL}}