Arc has an authenticated arbitrary local-file read via DuckDB I/O functions that bypasses RBAC table-level checks

Summary Arc's user-SQL validator internal/api/query.go:ValidateSQLRequest blocked only readparquet and arcpartitionagg via regex denylist. The broader DuckDB I/O function family — readcsvauto, readcsv, readjson, readjsonauto, readtext, readblob, glob, parquetmetadata, parquetschema, readxlsx, etc...