Ontology validator passes when there are mixed enumerations in the field list

Ontology validator does not fail (when it should) on a type like this; mixing of enumerated and non-enumerated fields should be invalid
```yaml
FDPM:
guid: "dc6d8a45-8ce6-4ac1-b5b5-cf9fd5727034"
description: "Filter pressure monitoring."
is_abstract: true
uses:
- filter_differential_pressure_sensor
opt_uses:
- filter_alarm
- filter_alarm_1
- filter_alarm_2
- filter_alarm_3
implements:
- MONITORING
```

Use the YAML example in the issue to reproduce the validator behavior, then locate the ontology validator entry point and its existing validation tests. Add coverage showing that mixing enumerated and non-enumerated fields fails, and confirm the regression test passes with the corrected validation.

Written by the indexing model from the issue text.