Function prepare_file_record 

fn prepare_file_record(
    integrations_root: &Value,
    action: &Value,
    file_record: &Value,
    request: &HttpRequest,
    input_overrides: &BTreeMap<String, Option<String>>,
    action_id: &str,
    entity_id: &str,
    event_kind: &str,
    anchor_record_id: i64,
) -> Option<(String, String, Value)>

Prepares an app-declared file effect without touching the filesystem.