NetBox now accepts case-insensitive model identifiers in configuration, allowing
both lowercase (e.g. "dcim.site") and PascalCase (e.g. "dcim.Site") for
DEFAULT_DASHBOARD, CUSTOM_VALIDATORS, and PROTECTION_RULES.
This makes model name handling consistent with FIELD_CHOICES.
- Add a shared case-insensitive config lookup helper (get_config_value_ci())
- Use the helper in extras/signals.py and core/signals.py
- Update FIELD_CHOICES ChoiceSetMeta to support case-insensitive replace/extend
(only compute extend choices if no replacement is defined)
- Add unit tests for get_config_value_ci()
- Add integration tests for case-insensitive FIELD_CHOICES replacement/extension
- Update documentation examples to use PascalCase consistently
