feat(schema): add scylla_task_id to backup_run_progress

A separate column for Scylla task ID is needed because:
- it has a different type from agent job ID
- it make it clear which API was used

pkg/service/backup/model.go

@@ -129,7 +129,11 @@ type RunProgress struct {
 	Unit      int64
 	TableName string
 
-	AgentJobID  int64
+	// Uploading SSTables could be done by either Rclone or Scylla API.
+	// Only one of those IDs should be set.
+	AgentJobID   int64
+	ScyllaTaskID string
+
 	StartedAt   *time.Time
 	CompletedAt *time.Time
 	Error       string

schema/v3.5.0.cql

@@ -0,0 +1 @@
+ALTER TABLE backup_run_progress ADD scylla_task_id text;