feat: add automated backups and Prometheus/Grafana monitoring stack (Steps 17-18)

Backups: pg_dump scripts with daily/weekly rotation and Cloudflare R2 offsite sync.
Monitoring: Prometheus, Grafana, node-exporter, cAdvisor in docker-compose; /metrics
endpoint activated via prometheus_client.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

monitoring/prometheus.yml

@@ -0,0 +1,36 @@
+# Prometheus configuration for Orion platform
+# Docs: https://prometheus.io/docs/prometheus/latest/configuration/configuration/
+
+global:
+  scrape_interval: 15s
+  evaluation_interval: 15s
+
+scrape_configs:
+  # Orion API — /metrics endpoint (prometheus_client)
+  - job_name: "orion-api"
+    metrics_path: /metrics
+    static_configs:
+      - targets: ["api:8000"]
+        labels:
+          service: "orion-api"
+
+  # Node Exporter — host-level CPU, RAM, disk metrics
+  - job_name: "node-exporter"
+    static_configs:
+      - targets: ["node-exporter:9100"]
+        labels:
+          service: "node-exporter"
+
+  # cAdvisor — per-container resource metrics
+  - job_name: "cadvisor"
+    static_configs:
+      - targets: ["cadvisor:8080"]
+        labels:
+          service: "cadvisor"
+
+  # Prometheus self-monitoring
+  - job_name: "prometheus"
+    static_configs:
+      - targets: ["localhost:9090"]
+        labels:
+          service: "prometheus"