WP-30/31/32: backup targets, strategies and execution

SMB (smbclient) and FTP/FTPS (curl with netrc) targets with encrypted
credentials and connection test; strategies with cron schedule, retention,
optional openssl AES-256 encryption; sources: PVC hostpath tar, pg_dumpall
in the Postgres pod, namespace manifests, host directory. Backup job
collects, encrypts, uploads, verifies size, records sha256 and applies
retention on the target; scheduler starts due strategies. Backups page
with target/strategy forms, run now and history. Restore guide in docs.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

backend/crates/api/src/openapi.rs

@@ -30,6 +30,10 @@ impl Modify for BearerAuth {
         crate::cluster::overview, crate::cluster::restart, crate::cluster::scale, crate::cluster::set_image,
         crate::vulnerabilities::list, crate::vulnerabilities::summary, crate::vulnerabilities::targets, crate::vulnerabilities::set_status,
         crate::settings::get_notifications, crate::settings::put_notifications,
+        crate::backups::list_targets, crate::backups::get_target, crate::backups::create_target, crate::backups::update_target,
+        crate::backups::delete_target, crate::backups::test_target, crate::backups::list_strategies, crate::backups::get_strategy,
+        crate::backups::create_strategy, crate::backups::update_strategy, crate::backups::delete_strategy,
+        crate::backups::run_strategy, crate::backups::records,
     ),
     modifiers(&BearerAuth)
 )]