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>

scripts/backup/pg-backup.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+set -euo pipefail
+
+# ── PostgreSQL Automated Backup Script ──
+# Runs daily via cron inside the pg-backup container.
+# Dumps the database and manages retention.
+
+BACKUP_DIR="${BACKUP_DIR:-/backups}"
+RETENTION_DAYS="${RETENTION_DAYS:-7}"
+TIMESTAMP=$(date +%Y%m%d_%H%M%S)
+BACKUP_FILE="${BACKUP_DIR}/goodgo_${TIMESTAMP}.sql.gz"
+
+echo "[backup] Starting PostgreSQL backup at $(date -Iseconds)"
+
+# Ensure backup directory exists
+mkdir -p "${BACKUP_DIR}"
+
+# Run pg_dump with compression
+pg_dump \
+  -h "${PGHOST:-postgres}" \
+  -p "${PGPORT:-5432}" \
+  -U "${PGUSER:-goodgo}" \
+  -d "${PGDATABASE:-goodgo}" \
+  --no-owner \
+  --no-privileges \
+  --format=custom \
+  --compress=6 \
+  -f "${BACKUP_FILE}"
+
+FILESIZE=$(du -h "${BACKUP_FILE}" | cut -f1)
+echo "[backup] Backup completed: ${BACKUP_FILE} (${FILESIZE})"
+
+# Prune old backups beyond retention period
+echo "[backup] Pruning backups older than ${RETENTION_DAYS} days..."
+PRUNED=$(find "${BACKUP_DIR}" -name "goodgo_*.sql.gz" -type f -mtime "+${RETENTION_DAYS}" -print -delete | wc -l)
+echo "[backup] Pruned ${PRUNED} old backup(s)"
+
+# List current backups
+echo "[backup] Current backups:"
+ls -lh "${BACKUP_DIR}"/goodgo_*.sql.gz 2>/dev/null || echo "  (none)"
+
+echo "[backup] Done at $(date -Iseconds)"