feat: backup safety — stop-before-dump, streaming restore, health check, per-app restic, infra configs (v0.34.0)

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

controller/internal/backup/crossdrive.go

@@ -25,6 +25,7 @@ type DBDumper interface {
 // VolumeDumper can dump Docker named volumes for a specific stack.
 type VolumeDumper interface {
 	DumpAppVolumes(stackName string) error
+	DumpAppVolumesSafe(stackName string) error // stops stack before dump, restarts after
 }
 
 // CrossDriveRunner handles per-app backup to secondary storage.
@@ -144,7 +145,7 @@ func (r *CrossDriveRunner) RunAppBackup(ctx context.Context, stackName string) e
 		if r.debug {
 			r.logger.Printf("[DEBUG] RunAppBackup: triggering pre-backup volume dump for %s", stackName)
 		}
-		if err := r.volDumper.DumpAppVolumes(stackName); err != nil {
+		if err := r.volDumper.DumpAppVolumesSafe(stackName); err != nil {
 			r.logger.Printf("[WARN] [backup] Pre-backup volume dump failed for %s: %v — proceeding with backup", stackName, err)
 		}
 	}