Schema validation rejects `read_only_background` property that was exported by a0deploy itself

[tonegawa07]

Description

`a0deploy export` outputs `read_only_background` in `themes[0].colors`, but `a0deploy import` rejects the same property with a schema validation error. This creates an inconsistency where the exported configuration cannot be re-imported without manual modification.

Steps to Reproduce

1. Export tenant configuration: `a0deploy export -c ./config.json -f yaml -o ./output`
2. The exported YAML includes `read_only_background` under `themes[0].colors`
3. Attempt to import the same exported configuration without any changes: `a0deploy import -c ./config.json -i ./output/tenant.yaml`
4. Import fails with schema validation error

Error Message

```
Schema validation failed loading [
{
"keyword": "additionalProperties",
"dataPath": ".themes[0].colors",
"schemaPath": "#/properties/themes/items/properties/colors/additionalProperties",
"params": {
"additionalProperty": "read_only_background"
},
"message": "should NOT have additional properties"
}
]
```

Environment

• a0deploy version: 8.18.0
• Tried with `--experimental_ea` flag: Still fails

Expected Behavior

If `a0deploy export` outputs a property, `a0deploy import` should accept the same property. The export/import cycle should work without requiring manual edits.

Additional Context

• The `read_only_background` property is documented in the Auth0 Management API v2: https://auth0.com/docs/api/management/v2/branding/post-branding-theme
• This issue occurs consistently across multiple environments

Current Workaround

Manually remove `read_only_background` from the YAML file before importing

[kushalshit27]

Thank you for reporting this issue! Our team is investigating the issue.