Add Prometheus + Grafana + Alertmanager monitoring stack

Full observability stack with Telegram alerting:

Components:
- Prometheus: metrics collection, 90-day retention
- Grafana: dashboards at monitoring.performancewest.net
- Alertmanager: routes alerts to Telegram bot
- node-exporter: OS metrics (CPU, RAM, disk, network)
- cAdvisor: container metrics (CPU, memory, restarts)
- postgres-exporter: PostgreSQL connection/query metrics
- nginx-exporter: request rate, 5xx errors, connections
- blackbox-exporter: HTTP/TCP endpoint probing + SSL cert checks

Alert rules:
- Service down (HTTP probe, TCP port, container missing)
- Container restart loops
- High CPU/memory/disk/load
- PostgreSQL down or high connections
- SSL cert expiring (14d warning, 3d critical)
- Slow HTTP responses, high 5xx rate

Blackbox probes all public endpoints:
  performancewest.net, api, dev, crm, lists, analytics,
  minio, crypto, pay

Telegram alerts: critical=1h repeat, warning=6h repeat,
  auto-resolve notifications

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

docker-compose.yml

@@ -285,6 +285,103 @@ services:
       - umami-pgdata:/var/lib/postgresql/data
     restart: unless-stopped
 
+  # ── Monitoring Stack ────────────────────────────────────────────────
+  prometheus:
+    image: prom/prometheus:latest
+    ports:
+      - "127.0.0.1:9090:9090"
+    volumes:
+      - ./monitoring/prometheus.yml:/etc/prometheus/prometheus.yml:ro
+      - ./monitoring/alert_rules.yml:/etc/prometheus/alert_rules.yml:ro
+      - prometheus-data:/prometheus
+    command:
+      - --config.file=/etc/prometheus/prometheus.yml
+      - --storage.tsdb.retention.time=90d
+      - --web.enable-lifecycle
+    restart: unless-stopped
+
+  grafana:
+    image: grafana/grafana:latest
+    ports:
+      - "127.0.0.1:3200:3000"
+    environment:
+      - GF_SECURITY_ADMIN_USER=${GRAFANA_ADMIN_USER:-admin}
+      - GF_SECURITY_ADMIN_PASSWORD=${GRAFANA_ADMIN_PASSWORD:-pw_grafana_2026}
+      - GF_SERVER_ROOT_URL=https://monitoring.performancewest.net
+      - GF_SERVER_DOMAIN=monitoring.performancewest.net
+      - GF_SMTP_ENABLED=true
+      - GF_SMTP_HOST=${SMTP_HOST}:${SMTP_PORT}
+      - GF_SMTP_USER=${SMTP_USER}
+      - GF_SMTP_PASSWORD=${SMTP_PASS}
+      - GF_SMTP_FROM_ADDRESS=noreply@performancewest.net
+      - GF_USERS_ALLOW_SIGN_UP=false
+      - GF_AUTH_ANONYMOUS_ENABLED=false
+    volumes:
+      - grafana-data:/var/lib/grafana
+      - ./monitoring/grafana-datasources.yml:/etc/grafana/provisioning/datasources/datasources.yml:ro
+    depends_on:
+      - prometheus
+    restart: unless-stopped
+
+  alertmanager:
+    image: prom/alertmanager:latest
+    ports:
+      - "127.0.0.1:9093:9093"
+    volumes:
+      - ./monitoring/alertmanager.yml:/etc/alertmanager/alertmanager.yml:ro
+    command:
+      - --config.file=/etc/alertmanager/alertmanager.yml
+      - --storage.path=/alertmanager
+    environment:
+      - TELEGRAM_BOT_TOKEN=${TELEGRAM_BOT_TOKEN}
+      - TELEGRAM_CHAT_ID=${TELEGRAM_CHAT_ID}
+    restart: unless-stopped
+
+  node-exporter:
+    image: prom/node-exporter:latest
+    command:
+      - --path.rootfs=/host
+      - --collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)
+    volumes:
+      - /:/host:ro,rslave
+    pid: host
+    restart: unless-stopped
+
+  cadvisor:
+    image: gcr.io/cadvisor/cadvisor:latest
+    volumes:
+      - /:/rootfs:ro
+      - /var/run:/var/run:ro
+      - /sys:/sys:ro
+      - /var/lib/docker/:/var/lib/docker:ro
+      - /dev/disk/:/dev/disk:ro
+    devices:
+      - /dev/kmsg
+    privileged: true
+    restart: unless-stopped
+
+  postgres-exporter:
+    image: prometheuscommunity/postgres-exporter:latest
+    environment:
+      - DATA_SOURCE_NAME=postgresql://pw:${DB_PASSWORD:-pw_dev_2026}@api-postgres:5432/performancewest?sslmode=disable
+    depends_on:
+      - api-postgres
+    restart: unless-stopped
+
+  nginx-exporter:
+    image: nginx/nginx-prometheus-exporter:latest
+    command:
+      - -nginx.scrape-uri=http://host.docker.internal:80/nginx_status
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    restart: unless-stopped
+
+  blackbox-exporter:
+    image: prom/blackbox-exporter:latest
+    volumes:
+      - ./monitoring/blackbox.yml:/etc/blackbox_exporter/config.yml:ro
+    restart: unless-stopped
+
 volumes:
   api-pgdata:
   worker-data:
@@ -297,3 +394,5 @@ volumes:
   erpnext-mariadb-data:
   listmonk-uploads:
   umami-pgdata:
+  prometheus-data:
+  grafana-data: