Add service health monitoring: postgres, node, cAdvisor exporters + dashboard

Exporters:
- postgres_exporter: DB connections, transactions, cache hit ratio, query stats
- node_exporter: host CPU, memory, disk, network
- cAdvisor: per-container CPU and memory usage

PostgreSQL:
- Enable pg_stat_statements for query-level performance tracking
- Track index scans vs sequential scans, cache hit ratio

Dashboard (service-health.json):
- DB: connections, size, transactions/s, slow queries, cache hit ratio, index usage
- Host: disk gauge, CPU, memory, network I/O, disk I/O
- BRouter: request latency p50/p95/p99, container CPU + memory
- All containers: CPU and memory comparison

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/cd-infra.yml

@@ -68,12 +68,19 @@ jobs:
             GHCR_TOKEN=$(grep DEPLOY_GHCR_TOKEN .env | cut -d= -f2-)
             echo "$GHCR_TOKEN" | docker login ghcr.io -u stigi --password-stdin 2>/dev/null || true
 
-            # Restart services
-            if [ "${{ github.event.inputs.restart_all }}" = "true" ]; then
+            # Check if full restart requested via:
+            # - workflow_dispatch input: restart_all=true
+            # - commit message containing [restart-all]
+            RESTART_ALL="${{ github.event.inputs.restart_all }}"
+            if [ "$RESTART_ALL" != "true" ] && echo "${{ github.event.head_commit.message }}" | grep -q '\[restart-all\]'; then
+              RESTART_ALL="true"
+            fi
+
+            if [ "$RESTART_ALL" = "true" ]; then
               docker compose --env-file .env up -d --remove-orphans
             else
               # Restart infra services (except Caddy — just reload its config)
-              docker compose --env-file .env up -d postgres prometheus loki grafana
+              docker compose --env-file .env up -d postgres prometheus loki grafana postgres-exporter node-exporter cadvisor
               docker compose exec caddy caddy reload --config /etc/caddy/Caddyfile
             fi