Fix: Error when clicking on reference links. (#647)

- Remove leading slash from S3 object key when generating pre-signed URLs.

backend/app/repositories/models/conversation.py

@@ -648,7 +648,7 @@ def get_source_link_for_schema(self) -> str | None:
         if url.scheme == "s3":
             source_link = generate_presigned_url(
                 bucket=url.netloc,
-                key=url.path,
+                key=url.path.removeprefix("/"),
                 client_method="get_object",
             )
             return source_link