Add filesystem-backed SSH credentials for the native systemd deployment
path. Generated keys are stored below POBSYNC_HOME with 0600
permissions, while Django keeps the public key, fingerprint, path, and
selection metadata.
Add a Django SSH key generation view, delete action for unused generated
keys, and a management command used by the installer to ensure a default
backup key exists.
Update runtime config to use generated key paths directly as IdentityFile,
extend host checks to verify key readability, and keep legacy uploaded
keys available for compatibility.
Add SSH credentials as first-class Django data so backup keys can be
uploaded through the control panel instead of mounted into containers.
Credentials can be selected globally or overridden per host. At runtime
the selected key is materialized inside the container with restrictive
file permissions and injected into the rsync SSH command via IdentityFile.
Known hosts entries are handled the same way when configured.
Add control panel views for creating and listing SSH keys, expose the
fields in config forms and admin, document the workflow, and cover global
and host credential selection with tests.
Introduce a ConfigSource interface so scheduled backups no longer need
to load host configuration directly from runtime YAML. Add a Django-backed
config source for SQL-driven backup runs, keep file-based config as the
CLI default, and make scheduled prune execution actually apply retention
after successful runs.
