Fix: add docstring to DocumentClassifierSchema for cleaner LLM tool description (#13315)

src/paperless_ai/base_model.py

@@ -2,6 +2,8 @@ from pydantic import BaseModel
 
 
 class DocumentClassifierSchema(BaseModel):
+    """Schema for document classification suggestions."""
+
     title: str
     tags: list[str]
     correspondents: list[str]