feat: add bounded task priority and fair application dispatch

pulse/service/service.go

@@ -55,6 +55,9 @@ func NormalizeSubmit(in SubmitInput) (SubmitInput, error) {
 	if err := ValidateConcurrencyKey(in.ConcurrencyKey); err != nil {
 		return in, err
 	}
+	if in.Priority < 0 || in.Priority > 9 {
+		return in, fault.Invalid("priority must be between 0 and 9")
+	}
 	if in.TaskTimeoutMS == 0 {
 		in.TaskTimeoutMS = 24 * 60 * 60 * 1000
 	}