feat: 每日自动备份数据库到 MinIO

- CronJob: daily-minio-backup, 每天 UTC 3:00 执行
- 备份 SQLite DB 到 minio-api.oci.euphon.net/oil-backups/
- 文件名: oil_calculator_YYYYMMDD.db
- 滚动保留最近 30 份，自动删除旧备份
- 使用 Python minio SDK 上传

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

deploy/minio-backup-cronjob.yaml

@@ -0,0 +1,96 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: minio-backup-creds
+  namespace: oil-calculator
+type: Opaque
+stringData:
+  MINIO_ALIAS: "oci"
+  MINIO_URL: "https://minio-api.oci.euphon.net"
+  MINIO_ACCESS_KEY: "admin"
+  MINIO_SECRET_KEY: "HpYMIVH0WN79VkzF4L4z8Zx1"
+  MINIO_BUCKET: "oil-backups"
+---
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: daily-minio-backup
+  namespace: oil-calculator
+spec:
+  schedule: "0 3 * * *"  # Daily at 3:00 UTC
+  successfulJobsHistoryLimit: 3
+  failedJobsHistoryLimit: 2
+  jobTemplate:
+    spec:
+      template:
+        spec:
+          containers:
+            - name: backup
+              image: registry.oci.euphon.net/oil-calculator:latest
+              command:
+                - sh
+                - -c
+                - |
+                  set -e
+                  DATE=$(date +%Y%m%d)
+                  export BACKUP_FILE="oil_calculator_${DATE}.db"
+
+                  echo "=== Oil Calculator Daily Backup ==="
+                  echo "Date: ${DATE}"
+
+                  # 1. Copy SQLite database (app does WAL checkpoint every 5min)
+                  cp /data/oil_calculator.db /tmp/${BACKUP_FILE}
+                  SIZE=$(du -h /tmp/${BACKUP_FILE} | cut -f1)
+                  echo "Backup created: ${BACKUP_FILE} (${SIZE})"
+
+                  # 2. Upload to minio and cleanup using Python minio SDK
+                  pip install -q minio 2>/dev/null
+                  cat > /tmp/upload_backup.py << 'PYEOF'
+                  import os
+                  from minio import Minio
+                  url = os.environ['MINIO_URL'].replace('https://','').replace('http://','')
+                  client = Minio(url, access_key=os.environ['MINIO_ACCESS_KEY'], secret_key=os.environ['MINIO_SECRET_KEY'], secure='https' in os.environ['MINIO_URL'])
+                  bucket = os.environ['MINIO_BUCKET']
+                  bf = os.environ['BACKUP_FILE']
+                  client.fput_object(bucket, bf, '/tmp/' + bf)
+                  print('Uploaded:', bf)
+                  objs = sorted(client.list_objects(bucket, prefix='oil_calculator_'), key=lambda o: o.object_name, reverse=True)
+                  for o in objs[30:]:
+                      client.remove_object(bucket, o.object_name)
+                      print('Deleted:', o.object_name)
+                  print('Total backups:', min(len(objs), 30))
+                  PYEOF
+                  python3 /tmp/upload_backup.py
+                  echo "=== Done ==="
+              env:
+                - name: MINIO_URL
+                  valueFrom:
+                    secretKeyRef:
+                      name: minio-backup-creds
+                      key: MINIO_URL
+                - name: MINIO_ACCESS_KEY
+                  valueFrom:
+                    secretKeyRef:
+                      name: minio-backup-creds
+                      key: MINIO_ACCESS_KEY
+                - name: MINIO_SECRET_KEY
+                  valueFrom:
+                    secretKeyRef:
+                      name: minio-backup-creds
+                      key: MINIO_SECRET_KEY
+                - name: MINIO_BUCKET
+                  valueFrom:
+                    secretKeyRef:
+                      name: minio-backup-creds
+                      key: MINIO_BUCKET
+              volumeMounts:
+                - name: data
+                  mountPath: /data
+                  readOnly: true
+          volumes:
+            - name: data
+              persistentVolumeClaim:
+                claimName: oil-calculator-data
+          restartPolicy: OnFailure
+          imagePullSecrets:
+            - name: regcred