Properties using the `InputFidelity` are missing the default

Documentation for the schema `InputFidelity` state that it has a default value of `low`. Properties where the type is used should include the  default value.

So, for schemas `CreateImageEditRequest` and `ImageGenTool`, the `input_fidelity` property would become:

```yaml
input_fidelity:
  anyOf:
    - $ref: '#/components/schemas/InputFidelity'
    - type: 'null'
  default: "low" 
```
