fix(guardrails/alice_wonderfence): narrow self.guardrail_name to str for mypy

Base CustomGuardrail declares guardrail_name as Optional[str]. Our
__init__ requires a non-empty value (factory rejects empty), so override
the attribute type after super().__init__() to satisfy mypy on
dict-key indexing in _stash_resolved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

litellm/proxy/guardrails/guardrail_hooks/alice_wonderfence/alice_wonderfence.py

@@ -158,6 +158,9 @@ class WonderFenceGuardrail(CustomGuardrail):
             supported_event_hooks=supported_event_hooks,
             **kwargs,
         )
+        # Narrow attribute type: base class declares Optional[str], but our
+        # __init__ requires a non-empty string and the factory rejects empty.
+        self.guardrail_name: str = guardrail_name
 
         key_suffix = f"***{self.api_key[-4:]}" if self.api_key else "<unset>"
         logger.debug(