Added content_hash field

Author: JosePizarro3

jsoned/models/schema_definition.py

@@ -1,5 +1,4 @@
 from datetime import datetime
-from uuid import UUID
 
 from pydantic import BaseModel, ConfigDict, Field
 
@@ -29,3 +28,8 @@ class SchemaDefinition(BaseModel):
         None,
         description="The actual schema content as a dictionary",
     )
+
+    content_hash: str | None = Field(
+        None,
+        description="A stable hash of the schema content for integrity verification",
+    )