Incorrect names for enum values

For a enum like this
```
"enum": [
"datetime",
"-datetime"
]
```
guardrail will generate two objects with same name `Datetime`

Start by reproducing the issue with the enum schema shown in the report, then trace the code-generation path that derives names for enum values. Determine how the generated objects are represented and what existing checks cover naming; done means the two values no longer produce duplicate object names and the relevant tests pass.

Written by the indexing model from the issue text.