Expose DELETE for application, database, and service storage backup
schedules (with OpenAPI docs), reject storage deletes while schedules
exist, skip retention cleanup when no limits are set, and remove S3
archives using the execution’s S3 storage.
Store s3_storage_id on scheduled volume backup executions so retention
and recovery use the S3 that received the upload. Extract
DeleteScheduledVolumeBackup for UI and resource deletion, and isolate
database backup retention failures so cleanup errors do not fail the job.
Add polymorphic volume backup scheduling for persistent volumes and directories, expose schedule management via API, and reorganize backup configuration and execution views.
