DX-119521: Support VIZ category in enterprise search results

Added VIZ to the Category enum in search.py to handle Dremio's
visualization search results without raising a Pydantic validation error.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ssaumitra

src/dremioai/api/dremio/search.py

@@ -85,6 +85,7 @@ class Category(UStrEnum):
     REFLECTION = auto()
     SCRIPT = auto()
     SOURCE = auto()
+    VIZ = auto()
 
 
 class UserOrRole(UStrEnum):