Add polymorphic volume backup scheduling for persistent volumes and directories, expose schedule management via API, and reorganize backup configuration and execution views.
Preserve S3 backups when a single valid storage is available, require
explicit selection when multiple storages exist, and disable S3 when none
are available.
Make backup action controls responsive on narrow screens.
Prevent scheduled database backups from enabling S3 uploads without a valid team-owned storage configuration, and preserve the previous S3 storage ID in missing-storage error messages.
Add coverage for backup edit/create validation and S3 upload failure messaging.
