Function build_sql_request 

pub fn build_sql_request(
    sql_op: &SqlOperationTemplate,
    context: &Value,
    renderer: &dyn TemplateRenderer,
    connection_url: String,
) -> Result<PreparedSqlQuery>

Build a complete PreparedSqlQuery from a SQL operation template.

connection_url is passed in already resolved — secret resolution stays in the main crate.