v0.15.5: Disaster recovery — Hub-based infra backup, auto-mount, restore UI

Complete DR implementation (TASK2.md Phases 1-4):
- Hub infra-backup push/pull endpoints (controller.yaml, disk layout, stacks)
- Fresh-deployment detection pulls config from Hub, auto-mounts drives by UUID
- Full-page restore UI with drive status, app table, sequential restore
- docker-setup.sh shows DR instructions when customer_id is configured

New files: disk_layout.go, restore_scan.go, restore_app_linux.go,
restore_drives_linux.go, infra_backup.go, infra_pull.go,
handler_restore.go, restore.html

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/settings/settings.go

@@ -292,6 +292,22 @@ func (s *Settings) GetAllCrossDriveConfigs() map[string]*CrossDriveBackup {
 	return result
 }
 
+// GetCrossDriveResticPassword returns the cross-drive restic password (read-only).
+// Returns empty string if not yet generated.
+func (s *Settings) GetCrossDriveResticPassword() string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.CrossDriveResticPassword
+}
+
+// SetCrossDriveResticPassword sets the cross-drive restic password (e.g., during DR restore).
+func (s *Settings) SetCrossDriveResticPassword(password string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.CrossDriveResticPassword = password
+	return s.save()
+}
+
 // GetOrCreateCrossDrivePassword returns the cross-drive restic password,
 // generating and persisting one if it doesn't exist yet.
 func (s *Settings) GetOrCreateCrossDrivePassword() (string, error) {