feat(ops): add database backup strategy and log aggregation stack

- Add pg-backup container with daily automated pg_dump (02:00 UTC) and 7-day retention
- Add backup/restore scripts with documented recovery procedure
- Add Loki + Promtail for centralized log aggregation from all Docker containers
- Add Loki as Grafana datasource with correlation ID derived fields
- Add Grafana logs dashboard with volume, error rate, HTTP request, and log viewer panels
- Configure Promtail to parse Pino structured JSON logs with level/context labels
- Enhance LoggerService with string-level formatter and service base field
- Configure 15-day log retention in Loki

Co-Authored-By: Paperclip <noreply@paperclip.ing>

monitoring/grafana/provisioning/datasources/datasource.yml

@@ -7,3 +7,15 @@ datasources:
     url: http://prometheus:9090
     isDefault: true
     editable: true
+
+  - name: Loki
+    type: loki
+    access: proxy
+    url: http://loki:3100
+    editable: true
+    jsonData:
+      derivedFields:
+        - datasourceUid: prometheus
+          matcherRegex: 'correlationId":"([^"]+)'
+          name: correlationId
+          url: '$${__value.raw}'