feat(dashboard): live GPU health scoring + real KPIs

- Added /metrics/gpu-health endpoint with live health scores (VRAM 40%, temp 30%, load 30%)
- Added /metrics/latency endpoint for dashboard KPIs
- Added GPU_LABELS for human-readable model names
- Dashboard v2: rewired to real data endpoints
  - KPI cards: GPUs online, circuit trips, avg latency, req/min, active requests
  - Health scores from actual gpu_health_score() function
  - Rolling 60-sample history chart (real data, no simulation)
  - Status: green/yellow/red based on tripped circuits
  - No CDN dependency (pure CSS)
  - Auto-refresh every 15s
- nginx: /dashboard/ serves static files with cache headers
- docker-compose: dashboard volume mount

Co-authored-by: Abiba <abiba@sysloggh.com>

docker-compose.yml

@@ -68,6 +68,7 @@ services:
       - "80:80"
     volumes:
       - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
+      - ./dashboard:/opt/inference-harness/dashboard:ro
     healthcheck:
       test: ["CMD", "curl", "-f", "http://127.0.0.1/health"]
       interval: 30s