Add Restic read concurrency setting

internal/model/validate.go

@@ -138,6 +138,9 @@ func ValidateJob(j Job) error {
 	if j.CPUCores < 0 || j.CPUCores > 256 {
 		return errors.New("cpuCores must be between 0 and 256")
 	}
+	if j.ReadConcurrency < 0 || j.ReadConcurrency > 64 {
+		return errors.New("readConcurrency must be between 0 and 64")
+	}
 	if j.Consistency.Mode != "live" && j.Consistency.Mode != "stop" {
 		return errors.New("consistency mode must be live or stop")
 	}