feat: backup app volumes before deployment

[aperolschpritz]

Summary

Adds automatic volume backups that run before a deployment is applied.

Behavior

• New per-schedule flags on VolumeBackup:
  • backupBeforeDeployment (default false) — opt in.
  • failSilently (default false) — continue the deployment when the backup fails; otherwise the deployment is aborted.
• Both are configured in the existing volume backup dialog.
• Before a deployment is applied, opted-in schedules run for:
  • the deployed app itself, and
  • all apps directly connected through app network policies (1 hop, both directions, same project).
• Backups run sequentially, one after another.
• Progress and errors are written to the deployment logs of the deployed app.
• The trigger hooks into deployment.service.createDeployment, covering UI deploys, rollbacks, webhooks and build-watch deployments.

Implementation

• Migration 20260924140414_add_pre_deployment_backup adds the two columns.
• getDirectlyConnectedAppIds lives in network-policy.service.ts.
• runBackupsBeforeDeployment lives in volume-backup.service.ts; backup.service.runBackupForSchedule encapsulates DB-dump vs volume-archive selection.

Testing

• yarn lint clean.
• tsc -p tsconfig.server.json exit 0.
• Integration test for connected-app selection, sequential execution and fail/silent semantics; affected unit tests green.